They're trying real hard to get the demo out before the game hits retail on August 21st. I'm kind of wondering if they're really at the demo stage if they're thinking that it won't be out before the retail date. Not only that, their reasons, in part include the following:

"We tried as hard as humanly possible to get it out to you guys simultaneously with the 360 demo, but we needed to make sure that it was perfect -- that all drivers were ready, and that the game looked great on a huge variety of computers."