Blizzard has just released a list of the overall class mechanics changes coming in patch 4.0.1, which we expect to go live tomorrow. This information, while not strictly new, is important to understand in that it will give a lot of insight to how your class is going to change before Cataclysm proper hits.
Remember that in patch 4.0.1, we're going to see the majority of the systems change in game, but not the actual world itself. The information given by Blizzard today is what it feels warrants a closer look at from the community.
The full Blizzard statement, after the break.