Mere hours after release, enterprising developers at the XDA forums have already obtained superuser access (root) on the HTC Thunderbolt. It is currently in private testing, and the developers are working to perfect the process before giving it a wide release.
With the HTC Inspire, root access allowed you to write to the /system partition, but once the device was rebooted all of the data would be discarded, leaving you with a stock ROM. Turning the security off (S-OFF) was required in order to write a custom ROM or a new Radio ROM. Fortunately, wth the Thunderbolt S-OFF is not required to write to the /system. However it is still required to flash a full ROM or change various low-level settings.
Currently the developers report there are some lingering issues to be resolved and expect a release soon, but it’s not quite ready yet. We’ll be keeping an eye open for the release, S-OFF, ClockworkMod Recovery, and custom ROMs which are sure to follow.