This morning Nethaera, a community manager with Blizzard, posted the following on the general forums: "Perhaps something will be occurring before [the release of Wrath]. I guess it's something we'll have to wait and see."
This comes in a response to a question asking if there will be a couple more surprises before Wrath of the Lich King.
Of course Neth is being her usual vague self here, not really committing to anything one way or another. But the comment does raise an eyebrow, and the fact that she even decided to respond to the question without a definitive "no" is good enough to speculate that there might be another world event headed our way.