TFS Beta 2 is just around the corner and it's going to be the first pre-release with a "go-live" license.  This means that we'll support customers putting it into production and we'll ensure upgrades from Beta 2 to RTM work so you don't lose any data.

Brian Keller wrote a great post about preparing for putting TFS into production: http://blogs.msdn.com/briankel/archive/2009/10/02/get-ready-to-go-live-with-team-foundation-server-2010-beta-2.aspx

We've been using TFS 2010 in production in DevDev since July and a few Microsoft IT teams since the Beta 1 timeframe.  We've also had a few TAP customers live for a while now.  It's been holding up very well and I expect people to have a pretty good experience with the Beta 2 builds.

Brian