I'm sure some are wondering if they will be able to connect to Team Foundation Server (TFS) 2010 from the existing Visual Studio 2008 Team Explorer. The good news is "yes," you can, but as of current you will have to provide the full construction of the URL in order to connect successfully. But there is a Visual Studio Team System 2008 Service Pack 1 Forward Compatibility Update for TFS 2010 that you need to install first. Here is the general form to connect to the TFS 2010 application tier:
Basically, providing this full construction of the URL in the Add Team Foundation Server dialog is fully manual and doesn't depend on the Port Number and Protocol connection details as specified in the section below the TFS server name textbox. TFS 2010 allows for multiple TFS application paths on one server (each of which maps to an IIS virtual directory), so you will now have to provide the correct path. Also, TFS 2010 has a new concept called Team Project Collections. A Team Project Collection is a group of related team projects within a TFS farm, and a TFS farm can host many Team Project Collections. By default, the first collection will be named DefaultCollection. You can find out much more detail about Team Project Collections at Brian Harry's blog here. So a typical construction would be as follows using all of the default options:
Now with all of this being said, there are some limitations when using the TFS 2005/2008 Team Explorer with TFS 2010, such as the inability to create team projects, since Team Explorer 2005/2008 are not aware of the newer features in 2010. The objective of the update is to continue to provide the experience of the 2008 client when working against a 2010 server. New functionality will require the 2010 client, but scenarios you already were able to perform in 2008 will continue to work. To get more info, there is a compatibility blog post with lots of information here.
Hope this helps. I will be blogging quite a bit on TFS 2010 and the transition from VSTS 2008/TFS 2008 moving forward.