Did you use starter fertilizer?
If not I would probably fertilize with something at this point.
You sound like you got pretty germination.
Maybe throw a little more on the thin spots.

It has been another week. Any improvement?

Fescues should germinate in 2 weeks. KBG will extend to 3 weeks. You should be seeing new KBG about now.

It's a little hard to spot the new grass within the healthier sections of my lawn, but when I get down and spread the grass around, I believe I'm seeing new growth - they are shorter and light green.

I have a problem areas where the grass really died off this summer, but I am getting very, very little new growth in these areas. My first thought for these areas is maybe there's a fungus, but would that prevent new seed from germinating?

In the areas of poor growth, what did you do to get seed to soil contact? Did you topdress? Can you see seed laying on the surface of the soil?

I raked out the dead grass before putting the seed down to ensure good soil contact. I did not top dress though, just ran out of time and wanted to get seed down ASAP. You mentioning top makes me wonder if these bare areas left the seed to exposed for birds to eat it up. I will look closer at the area and check to see if the seeds are still there and not germinating, or maybe find that it's all gone.

ranger,

To put it into perspective, I did an overseed about 5 weeks ago. I used Tall Fescue and Kentucky Bluegrass, and overseeded into a 10-month old PR/KBG lawn, going against common advice in so doing (I actually prefer lawn with the mixture of all three types, but maybe I'm the odd one out). And it did work, contrary to what people have said. In fact, it worked quite well. The existing PR did not prevent germination of the other grasses. However, I the lawn drastically prior to seeding, as you can tell, via aeration (three passes) and verticutting (two passes).

All the TF is up now. The KBG is about a week into germination at this point; I'm just starting to see it come up over the past few days. I'm currently touching up the few spots that need it with a little extra seed.

Here are some photos of the project (same area plus or minus a foot or two) at the various stages for reference (I do consider it a successful outcome even if it was my first time doing it and I learned a lot!):

The top photo is the before photo, taken on 8/17/12. The middle photo is about a week after overseeding, 8/29/12. And the bottom photo is from 9/21/12, immediately after the first mowing and application of start fertilizer (I decided to hold off on the fertilizer until after germination).

Good luck!

Meant to say I "thinned the lawn drastically" using the aerator and the verticutter.