Apple will be holding an iPad-centric event tomorrow at the Yerba Buena Center in San Fransisco, California. Honestly, that's all anyone knows at this point.
In the calm before the storm, speculation based on rumors based on leaks are all there is to go on. There's a good chance that Apple will address other products like MobileMe.
General consensus is that we'll also see a preview of iOS 5.0. An iOS 5 tease wouldn't be a stretch, especially with the probable release of the iPhone 5 this June.