The Revolutionary team has done it! Their bootloader rewriting tool now supports all gingerbread updates and many new phones, including the Thunderbolt. It is the same method to root the incredible 2 as it was with froyo, so you can still follow my how to video on YouTube. Below is a link to my How to Root - HTC Droid Incredible 2 video. Let me know if the updated tool works for you in the comments of that video!