It has been alluded by Aria T'Loak in Mass Effect 3 that she was ousted from Omega by the Illusive Man his Cerberus forces, but it seems we'll be getting the opportunity to take it back.
If you want to avoid any spoilers regarding the possible 'liberation' of Omega from Cerberus, into the hands of an Asari warlord, then don't read any further.
A number ofthat reveal Aria wants Shephard and crew to help retake the lawless Omega station, which was taken over by Cerberus through subterfuge and nearly resulted in Aria's death. Clearly the warlord is pretty ticked off and dangles the promise of further war assets in front of Shephard if they help.
Omega comes under blockade by Cerberus who is attempting to beat the populace into submission by starving its people. Aria wants the blockade broken but Cerberus is wise to the plan and, deeming the neutrality pack violated, decides to disable Omega's shields which would leave it defenceless to asteroid impacts.
Our mission, allegedly, will be to repel Cerberus forces looking to disable the station's shielding.
BioWare recently announced the existence of the Omega DLC as well as work on a new full instalment to Mass Effect. They also officially announced Dragon Age 3 as being in full swing for 2013. The studio also teased another big project underway but didn't elaborate any further.