Windows Messenger in Corporate Environments

   I had a surprise the other day - I run MSN Messenger 6.2 on my laptop here at work for occasional IM sessions with friends and family, and after I signed in yesterday morning with my user@microsoft.com Passport, it prompted me to change my Passport email addy to user@messengeruser.com! It told me to wait an hour to sign back in while they "upgraded" my account, and then later in the day when I did sign back in with MSN Messenger 6.2, it prompted me to download and install a special version of Windows Messenger 5.1 for my new corporate account... It was automagically configured to use both internal LCS SIP accounts and external .NET Passport accounts and seems to work fine. In fact, nothing appears to have changed here on the front-end so I'm kind of curious about what may have changed on the backend... I'm guessing that anyone with a user@microsoft.com Passport will have gotten the same prompts - Anyone know what's going on here?

-Bryce