Fingers crossed for today. Last year I don't believe the ps3 even got a demo until the week after it came out. At least if it doesn't come out tonight there will still be the Star Wars demo.
Edit:
SWEET
http://ps3.ign.com/articles/901/901502p1.html
We get it today, Live gets it in early september. Pretty strange. I've never seen the psn get a demo before live. I'm guessing it'll be up when the store updates this evening.