I reckon it'll eventually come to the PS3, but most likely next year since Microsoft would have definitely paid the money to keep it a times exclusive.
So, if I'm right, then I think what they'll do is simply release Mass effect 1 and 2 with all the downloadable content on 1 disc at full price, it'll be worth it that for sure, I know it would be late, but at the end of the day a good game will remain good despite when it's released...unless the port is broken to the shit house, then it's another story.