I'd probably check it out.Here is a link to a Blueberry growing study that Colorado State University did using coir as one of the components.I've used it in some of my containers,along with peat and things grew well. Brady

Here is a link that might be useful: Colorado State-Blueberries in Pot Project

I'd second Bradybb's thoughts, definitely worth checking out. Although I might be a bit suspicious as to why the GH is discarding it, disease issues maybe (but might be OK for you depending upon who's growing what)?

I have used coir in my blueberries (CSU's mix), as well as for other potted plant mixes. It is a nice "organic" substrate that absorbs water well yet still allows for air spaces.

Not sure how it would work in a compost pile, as one of it's main virtues is it is slower to break down than peat, bark and some other soil mix additives. But depending upon what you intend to do with your compost/soils, it may work well. If it were close to me, I'd grab it.