From the Mothership:
The Cube format is coming to Magic Online! Here’s what you need to know.
“Cube” is a format where players draft from a pool of cards that’s specially chosen to be awesome to draft. In this case, Tom LaPille designed a cube of 720 cards and Max McCall developed it, so you’ll have the opportunity to draft and play with some of the most powerful cards from across the history of Magic.
The Cube is going to be a limited-time event on Magic Online. Initially, it will be playable over the weekend of PAX East (April 6-8, 2012), and the inaugural event kicking this off will take place at PAX East, exclusive for that event’s attendees!
This is pretty awesome. Phantom drafts are cheap to play, and there’s nothing more fun than Cube drafts. If I had a PC, I would sign up for MTGO just for this. This had been speculated for a while, and now that it’s official I’m sure there are going to be some very happy MTGO players.