As you suspected, there is no official date yet. However, as you probably know, placeholder dates are "best guess" suggestions for retailers to list in their systems, so if you're seeing one placeholder date for August and another for September, you can pretty much count on whoever's listing the August date to have simply missed a memo somewhere. September is the much more likely of the two, though remember that even that isn't actually an announced release date -- it could still slip even farther back if things go wrong that we're not expecting. That's why we haven't announced an official date yet at all: because we're not confident we can stick to it, since there are still too many variables.
(This isn't to say August is impossible, of course. I just wouldn't count on it.)
-Tom
