If you haven't seen it regarding last weeks outage:
Microsoft: Human Error Was The Cause Of Five-Hour Instant Message
Outage
The service went out due to configuration errors when setting up new
routers that were -- ironically enough -- installed to make the
service more reliable.
http://update.internetweek.com/cgi-bin4/flo?y=eKGj0BfFir0V30BpZb0Ad
It's the interface between the chair and the keyboard...
Best regards,