Folks who have or are considering investing thousands of dollars to upgrade their old Prius or Escape will be out in the cold since the bill specifies "New Qualified" vehicles. The base credit would be $3,000 + $150 for flex fuel capability + $250 for every kWh of battery capacity over 5kWh (up to a maximum of $3,000). That would give a vehicle like the first iteration of the Volt with a flex-fuel engine and 16kWh battery a credit of $5,900.
It's not clear from the wording of the bill if a diesel hybrid that can run off of biodiesel as well as petroleum diesel would qualify for the flex-fuel credit. If this comes to pass, it at least takes the cost of lithium batteries partly off the table when it comes to developing mainstream PHEVs.
[Source: KXAN.com via Hugg, thanks to Linton for the tip]