The HTC Thunderbolt has been out for about -11 days, and already it has seen its first root attempt that led to a successful hack. They used was a pre-production Thunderbolt which they successfully rooted, cracked the internal memory, and installed Clockwork Recovery.
This means when you get your hands on the device, whenever it's released, you'll be able to root it as soon as you get home, and enjoy the unrestricted world of Android.
Source: Thunderbolt gets root and NAND access | Android Central
XDA: In the Name of Root [We Did It] - xda-developers