Byrd_Huntr, that's excellent information, thanks for the list! I checked the different plants out and currently they are all "pilot plant" scale designed more to test the technology rather than full-scale production plants. Still, it's a start.
They all seem to be using variations of acid hydrolysis to break down the cellulose down into yeast-friendly sugars. BlueFire Ethanol, Inc.'s technology page has a good description of the process. In the past this has been tricky to do on a large scale as it needs constant, minute tweaks to the batch as it is broken down otherwise you get a run-away reaction which can be very damaging. Advances in computer-controlled "tweaking" seems to be the key to these different plants. It'll be interesting to watch what improvements these companies make on the actual chemistry of the process.

-Blast