Bioware released six screenshots from the upcoming Mass Effect 3 DLC named 'Omega', viewable below. The four hour game extension will take place before the end of the game (and thus probably not impact it at all, for better or worse), and will see Shepard helping Aria take control of Omega back from the Illusive Man, for some reason or other.

Also, it will feature the first in game appearance of a female turian, if that sort of thing interests you.

The DLC will drop November 27th, for those who are interested in an avian alien capable of ovulation (say that three times fast).