In short, if you're a Limited Edition owner that didn't purchase the game secondhand, you'll be beta-eligible. Just make sure you've opted to receive email newsletters from your EA Profile. Those who "purchased a copy of Medal of Honor with the Battlefield 3 Beta sticker on it" are also eligible. Battlefield 3 is planned for an October 25 release on PC, Xbox 360, and PlayStation 3.
Some players recently received this beta reminder in their inboxes.