Things have started already, but they are just the first of the events leading up to Cataclysm. You may want to go to the major cities and hear what your leaders are up to. You also may want to make sure your earthquake kits are up to date too, you may start feeling the earth move under your feet.

Everything is not going to happen at once and we don’t want to give away any surprises. You’ll just have to keep your eyes and ears open as we march on toward December 7th. (Source)