They have been having issues for several days, and it was mentioned - in their front page news. This is the one from yesterday:

January 8, 2007 Server Outages
Our labstaff is going to be taking down milkyway for awhile to run some tests to see why it's been crashing so frequently. Hopefully it will be back soon running smoothly.

And the day before:
January 7, 2007 Server Outages
It looks like there have been some more power problems with the server, which is why it's been offline. We're working our labstaff to get these problems fixed.