It has been quite an exciting (and busy) night for Thrive owners and hackers. The community managed to root the device, enable Superuser Permissions, and flash ClockworkMod Recovery. Thus far only a handful of people have taken the plunge, so issues could still arise, but preliminary results are looking good. In their own words:
The gang at AndIRC - lead by Jamzelle and TheEndGame7 - has already managed to completely root the HTC Thunderbolt, and with Koush's help, has ClockworkMod Recovery up and running on the device. Apparently, it was a surprisingly easy task in just about every way.
The team started with a pre-production, unbranded Thunderbolt running a January 3rd ROM. What they found was that the phone had a bootloader with S-OFF, although they note that it's not an engineering bootloader, and that it's likely a different one than production models will ship with.