Bioware was talking a couple months ago about how they had an exclusivity deal with microsoft through the second game in the series. So that is why it hasn't gone multiplat yet. Give it 6 to 12 months after it comes out on the 360 and you will probably see it go to the ps3.
Although, depending on how well it sells, microsoft might try to extend the deal to keep it exclusive. I don't see them doing that though unless it sells over 4 million, which I don't see it doing.







