The mods over at MOULa obviously have gone Madagascar on this (AKA "SHUT. DOWN. EVERYTHING.") but this is the GoW and hence I'd assume everyone is happy to talk about it.
So.
What happened? According to a report over at the Myst Movie website:
"Details are still fuzzy, but there was a Rand appearance in the City, Bahro flying around, random spurts of anti-gravity, peoples’ KI text being changed, and psychadelic color changes. All kinds of interesting, but unsettling craziness."
We can assume that this isn't a Cyan prank to celebrate Rand's birthday, or indeed a Cyan event at all (because they'd use DRC members, not Rand), so it seems likely that the server's been hacked. Considering that Cyan updated the game to patch the security hole after the NotABeast incident, and threatened to bring down the server if further hacks occured, this is probably a pretty bad thing.
EDIT:EDIT: Ugh, okay, let's try this again because I'm a sugar-wired idiot.
Rand, the real Rand, did go down to the cavern, and on the topic of OS did say they were putting some stuff together and that "It won't be long now" before we get something. I do agree with Tweek that not being given a date or a timescale does make me go "meh", but at least Rand is confirming something is in the works pertaining to giving us lot something, and it's not far in Cyan-time.