The announcement on the login screen tonight tells us that the realms will be down for extended maintenance on Tuesday May 6th, from 3:00 a.m. PDT until 11:00 a.m. PDT. It's curious how extended maintenance used to last from five until eleven, but now lasts an extra two hours – from three until eleven.
Today we've seen the PTR (Public Test Realm) go down, and then come back up again. Earlier we thought this was a good indication that patch 2.4.2 was going to be released on May 6th, however with the PTR still being up, we don't believe that will be the case. Of course I could be completely wrong here – and we all might get a shiny new download screen tomorrow morning.
Only time will tell, and stay tuned to WoW Insider for the latest. We'll also keep you abreast of when the realms come back online, and any lingering issues that may arise.