It seems that in a recent patch for Mass Effect 2 on the PS3, BioWare has accidentally left some vague details of a possible downloadable content pack dubbed "Arrival".
The patch, which arrived within the last few days, included a set of trophies which suggested that the DLC pack will arrive that includes a new campaign. One trophy in the Arrival section called "Covert Action" refers to a Dr. Amanda Kenson, who was mentioned in the game's Cerberus Network:
"Historians and astronomers alike are abuzz tonight over a new paper published by Dr. Amanda Kenson of the University of Arcturus ... 'Only a small fraction of the mass effect relays date back 50,000 years,' she writes, 'The majority are far older, indicating they were created by a species predating even the Protheans.' ... What civilization could have spanned the galaxy for not thousands, but millions of years? If this were the case, we should have found mountains of evidence of their passing. Where is this species now?"
There is some speculation via the BioWare forums that it could be leading to the events of Mass Effect 3. Only time will tell.
Source: BioWare Forums