Ladder is being reset as we speak.

[Bashiok]

As an FYI people are being kicked out of games, we're going to verify all game servers are down, then take down everything. We'll push the patch, you'll be able to update and patch but character/game creation will be unavailable until the reset is complete. We're still estimating it all to be finished by 3:00 PM PDT, but updates will be posted in..

More...