Prevx has posted a follow-up on the 64-bit Windows rootkit TDL3: http://www.prevx.com/blog/155/x-TDL-rootkit--follow-up.html

Through some research it sounded like this new release was buggy, but they are doing a lot of stuff in there, and with their release cycle (they release new versions every day), I'm sure any bugs that do exist will get cleaned up quickly. Smart fellows over at TDL3.