Yeah the Devs are saying the Thunderbolt was the toughest HTC phone to unlock, but it is unlocked. So the Thunderbolt has a huge Dev following now, and the phone will have a lot of roms out shortly. MIUI and CM7 are already being worked on.
If the Bionic's bootloader wasn't encrypted then I am sure it would have a huge Dev following as well. But I bet a lot will stay away because of the Milestone and Droid X,2. Really a shame that it is encrypted though.