For some users it may be a bit offputting that taking one solution offline causes all other solutions bound to that same server to go offline when they are opened (assuming no "Go Online" operations in the interim).  There is a registry key value that may be specified to tell VS to ignore the server-based Offline setting and to only utilize the per-solution Offline setting.

To turn off server-based offline support:

  1. Go to the registry (e.g. regedit)
  2. Add a string value named, IgnoreServerBasedOfflineFlags, under 
    HKEY_CURRENT_USER\Software\Microsoft\VisualStudio\9.0\TeamFoundation\SourceControl
  3. Set the value to "True".

NOTE: My original text for this blog entry had stated that you set the value to "False" in step 3.  Obviously, this was incorrect.  Sorry for the confusion.