I thought these might help you:

See how the stems are bending over? They used to be completely upright, as this literally just happened overnight...
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An example of the yellow pattern of some leaves:
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Please help!

Hi Ostrich..Do you fertilize? It doesn't look like a fungus/disease..looks more like it's lacking something.
Maybe nitgrogen..(in the last pic of leaf)
Check plants for insects..though I don't think this is the cause, still it never hurts to inspect plants..Look for mealy bug which are good at hiding. Other pests while you're at it.
How much light are they getting? Jades require more sun than Peps...Though both are succulent, Peps prefer more humidity than Jades. Both like fresh air.
Are your plants in or out? Toni

Thank you, Toni!

I have not seen any bug... they have both been sitting at this location which is fairly near a south-facing window. It gets a fair bit of indirect light. They have been here for at least a year! They have both been doing great until just now... it is so sudden and so strange.

Maybe I will need to take it out and inspect the roots? I just don't understand how the leaves could look and feel so healthy and then suddenly the stems just BENT like this. Very odd indeed!

Ostrich, I had the plant you call Peperomia before but it died last winter..
Anyway, it's actually a Pilea peperomioides, (Chinese Money Plant) You can locate the pic at www.accentsforhomeandgarden.com (which is where I got mine)
It needs bright light, but nowhere near as much as Jades.
Other than overwatering, I can't figure out how it happened in a day either..that's strange..Usually when a plant is ill, it displays symptoms. Usually takes a while before serious problems arise.
The only time this happened to me, (which is why I mentioned pests) was w/a Coleus, several yrs ago..I didn't know what a plant bug was. So, one day I started reading my first plant book..the chapter discussed insects..I remember reading about mites..soon after I marched through the appartment, looking for these pests..sure enough my Coleus was mite infested..what's the chance of that happening? I swear to God, Os, the Coleus died that night..I didn't know about insecticides so didn't use anything other than taking to sink and cleaning off webbs..but that alone didn't do the trick.
Okay, how about pets? Do you have any that could have munched on stems? Or kids? Plucking leaves for fun..
I like your pots..they're really pretty..are they ceramic?
Oh do you fertilize? Toni

That is not a Pilea peperomiodes. It is a new Peperomia cultivar called Peperomia 'Jayde.' The leaves look similar to the plant Toni is thinking of, but note the difference in the stems.

Mine gets yellow leaves from time to time--usually if I have underwatered--and I remove them, with no ill effects to the plant. As far as the leaning is concerned, like many Peperomias, once 'Jayde' gets taller and heaver, the stems start to take on a less upright growth habit, and start to sprawl. I've been keeping mine propped up in the the corner of my window shelf, but eventually I'm going to let it do it's thing.

Toni, thanks again. Karen is right though, this really is a peperomia - it's the new cultivar, "Jayde". Anyway, I don't have pets (well, my plants are my children and my pets! LOL), nothing could have munched on the stems, no one has been plucking the leaves for fun. That's why I am completely perplexed! I do fertilize with Osmocote and sometimes with the Schultz liquid fertilizers. I just don't understand this overnight event! Sigh... by the way, Toni, thank you for your compliments on the pots! Yes, they are ceramic. I got this one from Target some years ago! Yup, Tar-shay does have some nice pots!

Karen, I see what you are saying, but then why would it just start to lean over just like that? It was just an overnight event! Yesterday morning, it was completely upright. Then by the evening, it was just bending over! How weird could that be?

it looks top heavy to me, could you clip it back where the joint is forming? It looks as tho it could be leaning towards the light that is far away but you said you had it in a sunny location. If it were mine I would snip it back at the joint and maybe put a stake in it to hold it up, You could probably stick the cuttings right back in the pot and they will take root since it's a succulent.My gramma did that with hers and she kept it snipped back, it got nice and full and eventually she removed the stake and it was more beautiful.

I don't know for certain, but I do have a guess about the sudden leaning. If you under-watered, it probably lost some turgidity in the stems, and began to lean. Even though the proper moisture level in the stems was restored when you watered, the stems, having gotten used to leaning, were too heavy to right themselves completely.

Your plant looks quite healthy. I wouldn't worry about it too much. I decided to prune mine today, as it really was very top heavy.

Karen, and Ostrich. Sorry about the error..I can't believe the resemblance..
Does anyone know of a site they have this Pep? Again sorry..Toni

Toni, here's a site where they've got info on the plant. The only error is that they call it Peperomia JayDe, when the plant tag, which I still have, calls it Peperomia 'Jayde'. It is one of those PPAF (plant patent applied for) plants, so I assume the preprinted tag is accurate.

And not to tempt you, but T & C Terrariums,(http://home.att.net/~a.j.calisi/plants.html) which I learned about from you, has it for sale. I didn't buy mine there though; I found it at a local nursery.

Here is a link that might be useful: Info about Peperomia Jayde

I would like to thank you all for your very helpful response!

I just took the plant out of its pot. The soil was moist and the roots were OK. I just don't know what was going on!

Usually, if I underwater the plant, the leaves would go floppy first by losing their turgor, but never the stems. This time, the stems are the ones that have lost turgor, but not the leaves!

I am going to snip them back as you suggested, and put the cuttings in a pot to see if I can start a new plant. Hopefully, as you said, I would get a better and fuller plant in the end!

Thank you again.

Karen, I now see one difference between the Pep and Pilea..the Pilea has round leaves w/o a semi-pointed tip like the Pep..
How in the world do botonist decide which plants are in certain families? LOL
T&C still sells nice plants, but like before, most are out of stock..I notice their prices increased..glad I ordered when I did, like the Vanilla orchid..
Thanks for the site..I'd never have seen a difference between the two..BTW, is the Jayde Pep similar to other peps, as far as care?

Ostrich, good luck w/your new plant..it's really pretty, and looks healthy..I'd follow Karen's advice about rooting. How long are stems from soil line to leaf? Karen might know if you need to cut back the stem before rooting. When you do root, use a well-draining soil. Though soil shouldn't stay wet, Peps like humidity. So, perhaps covering w/plastic would help plus speed root growth. Cut a slit in plastic for ventilation. I've rooted Pep cuttings in a reptile house which is plastic and lid has slits for air..cost less than 2.00 but that was some time ago. They shouldn't cost much more than 6.00..you wouldn't need a big house, something small would do well. They're also great for African Violet leaf cuttings. Good luck, Os, I hope you figure out the problem and get leaves to root..Toni

I have a Peperomia Jayde that I bought back in January at a local nursery. Here is a pic:

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Here is my other Peperomia (obtusifola? I'm not sure exactly). As you can see, it is definitely leaning every which way! I'm thinking of turning this one into a hanging plant eventually since it's starting to take up so much precious room by the windowsill!

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Here is the same plant a year ago - it's the one on the right. I had to get rid of the one on the left when I moved recently, since I decided to get rid of all "duplicate" plants. The one I kept was the older of the two, which I have had for five years. I think it began life as an "Exotic Angel"...

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One more thing: the pot that my Peperomia Jayde is in is made of compressed grain husks. It only cost about $3 and should last at least 5 years. I thought that was cool!

Toni, I acted fast! I just came back to post some new pics and then I saw your message.... thank you and I am glad that I did use some very good potting mix that drains very well. I also used the Miracle Gro rooting hormone, so hopefully they will take well!

Anyway, I gave my Peperomia Jayde a haircut and this is how the original and the new plants look now:

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Does anyone know what those brown spots are around the edge of that big leaf near the bottom? They have been there for a while...

Anyway, I found a weakened point (almost like a fracture!) in each stem and then just cut away. I shaved off about half the height. Here's the new "plant". I really, really hope that this works!

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Pepperomia, your plant is lovely! Mine was like that too, except that it was a bit taller. Your pot is gorgeous! Very nice indeed.

Good luck with the cuttings. I'm interested to know how long they take to root. Keep us posted!