We just released a joint case study based on the success that Thomson Reuters has had using Team Foundation Server in conjunction with Teamprise in order to adopt Team System in a mixed development shop.  Since the reality of many development teams is that they are dealing with some aspect of mixed development, I expect this to be a very popular case study to read.  Sharing a common, integrated source control system and collaboration server across the entire development team is a very powerful tool for teams interested in the successful delivery of great software (aren’t we all?) 

Here’s a great quote to whet your appetite:

“Without an integrated toolset, we had bits and pieces of information that simply didn’t mean much or make much sense,” says Mac Noland, Lead Software Configuration Management Engineer at Thomson Reuters. The lack of integration among tools made it difficult for Online Services to manage and report on projects. “Leads want transparency and easy reporting,” explains Noland. “People responsible for writing and quality checking the code want the ability to track history and associate change requests, defects, and bugs with specific lines of code. Lacking a big-picture view and the ability to drill down into the detail, we could not effectively manage the software life cycle.”

Anyway, take a look at the full details here: http://www.microsoft.com/casestudies/casestudy.aspx?casestudyid=4000002078.