I think that an actual release announcement would put even more consumers into a frenzy, creating a lot more buzz/pre-purchases. From a marketing stance, it's the perfect move.Even though I have no frickin' idea about marketing! I blame Arken, Retro, Jira, and Maxrpg!
You don't need to be a marketing wiz to know that throwing a single spark of news into a puddle of quietly-waiting gasoline creates a hype explosion.
The Beta Signup got a million people in ~48 hours on word of mouth alone. If every single one of those people gets an e-mail listing the release date this weekend right before the pre-purchase period begins...? Boom, baby.