The opening in game announcement tells us that there will be rolling restarts tomorrow beginning at 5:00 a.m. PDT / 8:00 a.m. EDT. Each realm will be down for about 15 minutes, and all the restarts should be done by 7:00 a.m. PDT / 10:00 a.m. EDT.
This is important in that shows patch 3.1 will not be going live tomorrow. No server downtime means no patch, so everyone can relax and enjoy the game as is for another week.
There is a possibility a few more realms will be down for an extended amount of time – and if that turns into anything major we'll let you know here.