The Microsoft ACE Team has put together a specific blog on Threat Modeling [found again (again as in I can't remember where I saw the original link over the weeked) through Jason Haley -- btw, check out Jason's new and improved site -- excellent work!].
This, I hope, will be a great resource. I have been impressed with the ACE Team's work, and the TM tool I have been testing recently from them will be a great resource for security people, and for those designing new systems and refitting old systems. Take a look.