We've lost track of just how many Gingerbread builds have leaked for the HTC Thunderbolt, but a new one's just appeared in RUU form. Ol' Football just dropped build 2.11.605.0. And being an RUU, it means you'll be wiping your phone if you run it in that form and don't want for a little additional hackery.
The good news is that work is obviously continuing on Android 2.3 builds for the 'Bolt. So hopefully we'll have a relatively bug-free upgrade when the time comes. (Knock on wood.)
Source: XDA Developers; Thanks, Brian!