From the Department of Friendly World of Warcraft Reminders comes a note on the pending patch 5.4, scheduled to drop next Tuesday: connected realms will not be turned on at the release of patch 5.4. Instead, they're going to be turned on gradually and fine-tuned as time goes on.
We've been seeing a lot of confusion over this, and rightly so -- it's a major feature of the patch. However it's not uncommon for Blizzard to slow walk things out the gate, they do this with raiding and LFR, and in the case of a major game change that is essentially merging servers, it needs to be done extremely carefully.
No doubt that when it does get turned on most of the world will erupt in one form or another. We're pretty sure you'll be able to hear it, and we'll be covering aforementioned eruption here as well.