We're really excited that our colleagues over in the SDL team have released a beta of their threat modeling tool, as one of several SDL-related announcements.
As threat modeling matures as a discipline, there's no single 'right' way to do it. Both the TAM tool and the SDL tool address specific needs that our user communities have. The SDL tool is intended to be software centric, while TAM is asset centric. It's great to be in a situation where we can really distinguish between these and make tools which are focused on the needs of the different customer groups.