The demo will launch on Xbox 360 worldwide and PS3 in North America on February 21; the PS3 demo will be available a day later in the rest of the world. It will feature one playable character, Zoe -- Mac is unlockable through a referral system that EA has yet to reveal -- and two tutorials, plus two events and skydiving.
[Thanks, Jack.] Update: Added more detail via @kfatyas. Thanks!