yeah it was only supposed to take place in the morning though - if you check the major hryb nelson link there, you'll see they created connection issues that lasted quite some time. Looks like all is well now, though.
Most likely that they're shoring up the XBL system in prep for the Halo 3 onslaught. It would be a PR mess if XBL was crapping out when Halo 3 launches.