It is held in the ABC Theater to the left of the Sorcerer's hat about 4 times every day (Fri.-Sun.). There's not much on Episode III, in fact they don't even give the title of the movie. They spend most of the 20 minutes in behind the scenes footage from the first two Episodes, and maybe the last 5 minutes on Episode III. Basically building of props and making a big deal about the script being finished! The most revealing piece of information they revealed is the fact that there will be a serious fight between Anakin and Obi-Wan, obviously not to the death! They also introduced some sort of energy staffs, that are impervious to light-sabers. That's the problem with these movies; the technology in the first 3 episodes seems to be more advanced than in Episodes IV, V and VI.
Oh, by the way, Episode III is scheduled to hit theaters in May, 2005!