Interesting problem. Can you provide any details about your configuration? Hard telling, not knowing. I can't repro on any of my machines.
This is a bug that needs to be fixed. Thanks for alerting us of it.
For the Wiki Passport bug... When the HttpContext.User.Identity is a PassportIdentity, the User.Identity.Name value is the PUID of the PassportIdentity, not a Channel 9 Username, which is the case when the Authentication type is Forms.
Passport has no way of knowing that your PUID (your Passport unique identity) is asscociated with some string value in an application that uses it's auth services... When you are logged in using Forms auth, the Identity.Name value is your auth username, which is your C9 username.
I haven't spent much time thinking about a solution, but I do know that it will require a fair amount of work. This doesn't mean we won't fix it, of course. Just need to spend some quality time on the solution.
Keep on posting,
C