A listing for Mass Effect 3 popped up on the EA online store today, and a plot description describes a fight to take back planet Earth.
The listing for the PC version of the game was spotted by gaming blog Destructoid today. The official summary on EA’s store states:
Earth is burning. Striking from beyond known space, a race of terrifying machines have begun their destruction of the human race. As Commander Shepard, an Alliance Marine, your only hope for saving mankind is to rally the civilizations of the galaxy and launch one final mission to take back the Earth.