Wow, ask and ye shall receive! James Manning has released an initial implentation of an MSH provider for TFSC. Make sure to check out the MSH Community Workspace, where he contributed the source, too!

Update:
James contacted me to let me know about two things:

  1. I had a little typo in the title (“TSFC” instead of “TFSC”) which I've fixed
  2. I should probably be calling it TFVC from now on... Team Foundation Version Control vs. Team Foundation Source Control.

Thanks James!