Visual Studio 2005 onwards, watch window has got a pseudo register for investigating the details about process token. So, all you have to do is, just start debugging and write "$user" in watch window,
Its interesting to look at expanded view of privileges and groups sometimes!
Heh, must not be a commonly used feature if the misspelling of the LUID field as "Loggin Id" instead of "Login Id" made it into 2008 RTM.
That aside, a great feature to take the mystery out of tokens and impersonation. Windbg provides a similar capability in the form of the !threadtoken extension command.