Wizards of the Coast has announced that it plans to release Magic the Gathering: Duels of the Planeswalkers on Steam. Unfortunately an actual release date has not yet been confirmed by WOTC. We're guessing the date isn't too far off, as the game will be available for pre-purchase on Steam starting June 1. Those who pre-order Planeswalkers for $9.99 will receive both the original game as well as its first expansion pack, which was released last year on XBLA.
The release will also support future content. A second DLC pack is already available on XBLA, with a third pack expected this summer.