Well, one thing is pretty obvious - EA are going to want everything with a chance to sell well multi-platform to be multi-platform, that's a no-brainer.
As for ME games specifically, they will put in on PS3 if/when contacts allow and if they believe they will get sufficient sales to justify it. BTW I believe Bioshock sales on PS3 actually would justify it, as given the circumstances it was never going to sell much more but it gets the franchise on the PS3 and is Bioshock 2 opens on both at the same time it is sure to sell much better on PS3 than 1.
So for ME its down to what contracts MS had with Bioware and what were the terms of the purchase and where it leaves ownership of the IP and the current ME game specifically.
Some contracts, if they don't explicitly cover change of owner, become null-in-void - i.e. if MS/Bioware contract did not provision for change of owner then EA might have a free hand. This would surprise me though, adding something for change of owner is pretty standard and I would imagine MS lawyers get paid enough to make sure it would be in place to cover anything MS was sinking money into.
More likely I think is that ME 1 remains 360 due to contracts but EA are probably otherwise free to steer any other ME games to PS3 as well as I suspect they own the IP fully now in terms of its usage.
No company in EA's position is going to want a title like this exclusive to one platform when they have most of their more recent games selling well on both PS3/360 and stand to make more money by serving both install bases.
Try to be reasonable... its easier than you think...
