1UP was in attendance at BioWare's GDC panel hosted by "localization experts" Ryan Warden and Chris Christou, and they've since posted an entry to their RPG blog summarizing the discussion that took place. An excerpt:
BioWare also provided a glimpse of their Character Bible during the presentation, which I also found extremely interesting. The slide they put up had categories including species, age, general description and importance to the plot, and apparently would have stretched to the opposite wall if they had shown the whole thing. One character that was listed on the excel sheet was Admiral Han'Gerrel vas Neema, who appeared briefly during Tali's loyalty mission (spoilers, perhaps?). His importance to the plot was listed as "medium," and his description was as follows:
"Han'Gerrel is an old friend and comrade of Tali's missing father. He treats Tali like a niece, friendly and comforting in talks both before and after the trial. Han is, however, a firm believeer in the war with the geth. If the trial outcome does anything to hurt that, Han is incredibly angry with Tali."
Mass Effect 2 alone has some 571 more characters of varying importance beyond Han'Gerrel, of varying importance, and BioWare keeps detailed tabs on them all. It's been said before, but this panel only reinforces in my mind that understanding BioWare RPGs simply means understanding their approach to the dialogue and the characters. One interesting comment from Warden was that BioWare is always on the lookout for voice acting on the level of a film or television show in their games, which can be difficult to find at times.