EA and Bioware have just let everyone know that a demo for the duo’s latest and greatest space opera RPG, Mass Effect 2, is now up and available on Xbox LIVE Marketplace.

In addition, Mass Effect 2’s latest set of downloadable content (DLC), Overlord, has been announced to become available very soon for those who’ve already got the game.

The 2 GB Mass Effect 2 demo (currently only available to Xbox LIVE Gold members) will give players a 90 minute preview of the game, and allow them to “step into the role of Commander Shepard,” who must “escape from a Cerberus space station under siege.”

“Players can jump ahead to a later mission where they must rescue Subject Zero, a hardened, dangerous criminal from a heavily guarded prison ship.

“Once they play the demo, players will be able to create a save and carry over their character along with the experience points, story decisions, achievements and weapons earned into the full version of the game – picking up right where they left off, on both PC and Xbox 360.”

The Mass Effect 2 Overlord DLC will become available tomorrow (June 15th) for 560 MS Points on Xbox 360, and 560 Bioware Points on PC.

Bioware will also be releasing a new premium theme based on Omega on June 15th, as well as new avatar items for Xbox Live on June 17th.