Bioware, on it's community forums, has stated the first available downloadable content for Mass Effect will be released on March 10 at 2am PST time on Xbox Live. The download will cost you 400 points.

From their post:

"Bring Down the Sky includes a new uncharted world that introduces the notorious and feared alien race of the Batarians. A Batarian extremist group has hijacked a mobile asteroid station in the Asgard system, setting it on a collision course with the nearby colony world of Terra Nova. Only Commander Shepard can save the millions of innocent civilians before the asteroid completes its deadly descent.

Bring Down the Sky contains approximately 90 minutes of heart-pounding action and a new Achievement worth 50 Gamerscore points"

Will this be on the PC version? I hope so...

Only 400 points to endanger millions of lives?

I'M THERE!

Seriously though, don't quite see this as worth it. Mass Effect had trouble holding my attention, and an extra planet wouldn't help, really.

Does sound like the plot of a very bad b-grade sci-fi doesn't it.. lol

What happens if you want to kill the innocent civillians?

It's the first of at least 5 expansion missions.

So we get to kill them in the later missions then?

coool...

i bought mass effect the other day, and although its pretty short i loved it and i will be buying the DLC's as they are released.