The TFS release candidate was released a coupe of days ago on MSDN downloads (http://msdn.microsoft.com/subscriptions/).
After waiting half a day for the files to come down the installation was pretty much a breeze. Of course after having installed the previous betas the expectations on the setup wasn't too high... My first attempt was at a single-server installation running as its own domain controller. I started of by uninstalling the old TFS according to the docs. After that I started the TFS setup. This turned out to be a bad solution since the RC won't install on a machine acting as DC. I tried to demote the machine but that broke most other components so I had to reinstall the server, this time as a stand-alone server. After that the install procedure worked pretty well. SQL Server installed fine. I had to stop the SQL Brower service while installing the KB912838 since some files apparently were in use but that was all. An hour later or so I had created a new Team Project!
So far this TFS version seem to be in good shape. Performance is a major difference but there are many changes since beta 3.
The latest version of the setup guide can be found here: http://go.microsoft.com/fwlink/?linkid=40042. Do follow it in detail in to get a smooth install of TFS. So for once its a really good idea to RTFM up front...
There is also a utility to upgrade from TFS beta 3 refresh to TFS RC at http://go.microsoft.com/fwlink/?LinkID=60341.