Here's the latest on Brian Harry's blog: http://blogs.msdn.com/bharry/archive/2008/01/09/jan-08-devdiv-dogfood-statistics.aspx. Keep in mind that this is just for DevDiv (Developer Division) ... so we're talking about the developer tools (i.e. Visual Studio, etc). There are other groups using TFS inside of Microsoft. Looking at this ... wow ... it gives you an appreciation of the amount of development that is done here.
Speaking of TFS, I heard a customer story about TFS recently that really speaks to the value. So ... a remote dev center was coding away on an application, but Central IT noticed that they had a lot of bugs being re-opened and that overall, things didn't seem to be going too well. Of course, re-opened bugs ... well ... that's definitely a problem. This was exposed to the Central IT team through the OLAP and reporting capabilities of TFS. But the data and processes ... well, it's easy and natural for devs to work with so they tend to actually do it. Having the working items completely integrated into VS and into your check-in process was a huge thing for me. So ... Central IT was very concerned and they had the remote team come down to see them. They went over what was going on. As it turned out, the remote team didn't have a clear idea of the vision of the project and this was leading to a lot of issues. They got this resolved ... and the team got back to work. This time, though, the stats were better. It took the business another 3 weeks to notice this; by that time, the underlying issue had been corrected. Three weeks of development time that would have been ... ummm ... less than productive had already become very productive. It saved 3 weeks on a time-critical project. And, of course, the largest cost of a software project is the people ... the developers' time. Well, I thought it was cool.