This thing is still being nailed down and about as clear as mud, but here is what I know up to this point...
The 30% tax credit will be for biomass burners rated at 75%+ efficiency. The credit is in place for 2009 and 2010. Pellet stoves will mostly likely qualify since they have a default EPA rating of 78%. Since wood stoves are rated at either 63% or 72% by the EPA, it is up to the wood stove manufacturers to pay for and submit their products for testing, if they choose to do so. If they pass, their certification will have to be posted on their site.
IMO, most wood stoves will probably not pass this testing. The wood stoves that have the best chance of passing are cat stoves. Off the top of my head, I believe Blaze King and Woodstock are going to be having their cat stoves tested, it's unknown what the results will be, although both are hopeful and optimistic that their products will pass.