A developer named dbzfanatic over at XDA has put together the first one-click easyroot + S-OFF for the HTC TBolt. Here's his description:
This looks very slick, although keep his disclaimer in mind when trying this out. After any of you guys try this out, let us know in the forums how smoothly the process went. Of course, below is the link to the XDA thread to get more info, and the download links.This is my easy-rooter for the Thunderbolt. I do not personally have a thunderbolt but I have tested it and fixed as many problems as I could. As far as I'm aware this will only work with firmware versions lower than version 1.12.605.9.
If adb does not see your device try installing the htc sync drivers. If that doesn't wok install PDA.net. If it still does not register please post here.
THIS IS A WINDOWS-ONLY PROGRAM. You must have windows or a windows VM to use this.
As always there is a small chance of bricking your phone.
DISCLAIMER: AndIRC is not affiliated with this program and by using it you agree that neither AndIRc nor myself is responsible for any damages caused by this program.
This provides all necessary files and gives you in-program instructions.
Source: AndroidPolice via XDA Developers