One step taken and a thousand miles to go... Jason Bentley has created a new workspace on Gotdotnet called NTeam, which he describes as,

[Jason Betley on] "NTeam will be an open source alternative to Team System, will make use of the open source projects all ready available such as NUnit, NAnt, etc., and will target small- and mid-sized development teams. If you are interested in joining the workspace, join through the project page. I am really excited about this project and hopefully, it will fulfill the needs of those teams feeling shunned by Microsoft."

As a former member of the Team Foundation team, all I can say is "good luck and godspeed" guys. The march is long but the treasure is real. It's awesome that you're doing this on