Among the overlays seen on Android phones HTC’s Sense is probably the most popular. That being said, the “pure” Android experience is usually preferred over all else. Although this modification doesn’t represent a full AOSP experience it does help add a small glimpse. XDA member Master™ has created a script to nix the stock Sense lockscreen on the Thunderbolt which we cause it to default to the regular AOSP lockscreen.
The lockscreen is flashable via ClockWorkMod Recovery and requires that your device be rooted. The only modification that takes place is the removal of the stock HTC sense lockscreen files. As with anything else backing up your existing setup is recommended. Download links and instructions can be found in the XDA thread.