There's very little chance of ME 2 or ME 3 being on the PS3. Microsoft has done everything possible to keep Mass Effect as a X360/PC exclusive, and I doubt that with 2m+ units sold that Bioware has a big reason to release ME2/3 on the PS3, as you'd have to also re-release ME1 on the PS3, which adds more cost to the equasion.
Now, BioWare/EA could release the ME triliogy once it's completed on the PS3 - maybe even 1 BR-DVD if they wanted to. But I doubt it'd be within ~6mo of the trilogy being completed on the 360.
Now, as for the PC, I think that since MS is publishing it, that they will try to do day-and-date for the PC side of things.
Again, just because EA bought Bioware doesn't mean they can throw out any written contract that they've made with Microsoft. EA could easily of published ME2 by themselves, but MS is doing it. If MS is publishing the PC version, why in the world would we expect everything else to change, to fit PS3 fanboy desires? Not every game is going to be on the PS3, deal with it.