Official hours won't be released probably until October, or more likely, November. But my bet guess would be:
Magic Kingdom: 9-6 M-F, 9-10 Sat, Sun
Epcot Future World: 9-6 daily
Epcot World Showcase: 11-9 daily
Disney Studios: 9-8ish daily (I think...I'm really not too sure)
Animal Kingdom: 9-5 daily
This past January, there were extended hours at the Magic Kingdom on a couple of nights, but those were approximately the hours in January 2002. (And January of 2003, like I said, with the exception of a few nights until 8:30 at the Magic Kingdom)
And yes, the hours fluxuate a lot between January and May. They fluxuate with the crowds.