OK, so this is for all those people using beta builds out there. There is a client side cache involved with connecting to remote TFS application tier machines. Unfortunately it can be somewhat buggy in the beta builds, leaving you with an error message like this when you try to connect:
Microsoft Visual Studio
Object reference not set to an instance of an object.
If that is the case, try this trick (from a Visual Studio command prompt with devenv in the path):
This will clear everything (including maybe some custom settings you didn’t want to have to retype in again) but the next time you start devenv you will have to go through setting up your user information again but you should be able to connect to the TFS site without this error message blocking you.