As a follow up to my post back in August when we put TFS Beta 2 onto our production box, I just thought I'd mention that here at Teamprise we have now been running Visual Studio Team Foundation Server 2008 for over 6 months now. We recently upgraded our production TFS instance to the RTM release of TFS 2008 and everything is going very well.
The Microsoft team have done a fantastic job with compatibility which meant that we didn't even need to re-compile Teamprise to get it to work with TFS 2008 and still get all the performance benefits from the server. The current public versions of Teamprise work great with TFS2008, as does Visual Studio 2005.
While TFS performance has improved since the RTM of TFS 2005, for me the single biggest reason to upgrade to TFS 2008 are the new and much improved build capabilities. As you might have guessed by the number of Team Build related posts on my blog lately - in the next version of Teamprise we will be including integration with Team Build. This has been my area of focus for most of this year so I am really excited to see what people think once we make it available.
In the meantime, if folks are considering upgrading to TFS2008 from TFS2005 then I would certainly recommend it. The upgrade from TFS2005 to TFS2008 has been very smooth in my experience.