An EA Sports spokesman has said that a week from tomorrow, through an unnamed media outlet, the final word on the Madden NFL 11 demo's release date will be given. The smart money has it arriving July 23.
That's unconfirmed through EA Sports, but it would conform to past practice. Last year, EA Sports rolled out its full team ratings over the course of several days via ESPN, and is doing the same thing this year. The blog GoMadden got its hands on the ratings release schedule, and notes the last ratings release day is July 22. Last year's demo came out the day after all team ratings were known.
An EA Sports spokesman earlier confirmed that this year's demo would feature five-minute quarters, in order to showcase major game changes such as the new GameFlow model of planning a game and calling plays. EA Sports said the demo will also offer "some surprises", with scuttlebutt being on free DLC tie ins with the main game, similar to what NCAA 11 did this year.
As for who gets the exclusive on the demo reveal, my money would be on either ESPN, GameInformer or IGN, but who knows. It ain't me, that I can confirm.