Though we haven't seen official word on the topic yet, it's expected that the next wing of Icecrown Citadel, the Plagueworks, will open tomorrow once realms come back online. This wing will include the bosses Rotface, Festergut, and Professor Putricide. Personally, I wouldn't be surprised if we also saw a minor bug fix patch tomorrow, but only time will tell.
If we hear anymore regarding either of those things throughout the day, we'll be sure to keep you updated.
Edit: I know how to use a calendar. Really. I do.