Microsoft scheduled a very interesting initiative for the 13-15 September: the Team Foundation Server 2013 Upgrade Weekend.
What is that? It is a weekend where organizations can upgrade their Team Foundation Servers to the 2013 release with the latest go-live prerelease, and get free support in case of issues by the Microsoft CSS.
I strongly suggest to join us (I am going to upgrade several instances as well, both personal and corporate), to do this you are simply required to register here so they can staff the appropriate people.
If you need to download the previews, here you can find what you might need!