New iMacs coming August 31st

They said it would be September, and now ThinkSecret reports that Apple is going to offically announce the next-generation iMacs on August 31st and that they'll start shipping them a couple of weeks later on September 15th.
Everyone seems pretty sure these'll sport a G5 processor, so the only big unknown left is whether these will be
"headless" iMacs that come without a built-in LCD screen.