This outage is ahead of schedule according to the status page which displays the following message:
Due to scheduled maintenance, MobileMe members will be unable to access most of the web applications via me.com. However, members can still access Find My iPhone or Account by manually typing me.com/find or me.com/account respectively. Normal service is expected to be restored at the end of the maintenance window. We apologize for any inconvenience.and says the outage should be between January 20, 2011 at 22:00 PST and Jan 21, 2011 at 00:00.
Update: Although I was able to duplicate the problem on two machines - I have now gotten it working on both but by trying a different browser. Also, the iPhone app seems to be working.