Just announced at the Microsoft Conference at E3. Resident Evil 5 will be released on the 13th of March next year (2009). They showed off a bit more of their co-op play and talked a bit about the new organization that isn't Umbrella. So we could maybe see a demo hit by October. Or at least at any other Conventions that Capcom will be at.
On a separate note, www.residentevil.com has been changed up a bit with a new flash video. I'm sure all of this will be updated on their site once they do their announcement at their press event. Check it out. Can't wait for March now.