I must be on a little patterns & practices binge right now now as this is my third post in the past week on something associated with them. Anyway, J.D. has posted a brief description of how they organize their source trees within TFS.  One thing that we've realized in talking with customers is that while we did a good job of providing the tools and platform for team based development, we still have a ways to go in providing descriptions of the best ways to use these tools to get great results.  Some of it's included as part of the Microsoft Solutions Framework and certainly many blogs around the world, but we need to pull it together into a common location in an easily digested format that has been endorsed by our team.  It's something we're working on but for now, these sorts of blog entries can help.