With Namco's relationship with Microsoft (Tales of Vesperia, Beautiful Katamari, Ace Combat 6, Culdcept Saga, Eternal Sonata, Warhammer: Battle March), Tekken 6 seems to be not only likely but almost a certainty at this point. I do expect it to spend a few good months on PS3 first though, the same way Virtua Fighter 5 did. I'm almost positive 360 will see Tekken 6 as it'll have the similiar buying audience from Soul Calibur IV. 80% chance.
Next up is Disgaea 3. Atlus already has been publishing small series onto the 360 and NIS will want in on the action. This game isn't going to sell much on PS3, but may have a decent chance for a few more sales on 360 since there's a built in RPG fanbase, just not a large one. 50/50 shot I say.
Valkyria Chronicles is very likely. SEGA has not been very exclusive friendly this generation, and again, PS3 is a complete unknown with selling RPGs. SEGA will recoup more by making this multiplatform and I've got a feeling they will. I also hope they will because I won't feel so forced into having to get a PS3. 60% chance I think.
Metal Gear Solid 4 I doubt is happening. It's doing fine sales wise. It'll stay put. 30% chance of happening if that.
Heavy Rain is going to happen unless Sony already paid for this game. There's just no logical reason for them to not include the 360. 90% chance of happening and even then I think it'll bomb.
BlazBlue will happen for sure. It's niche to begin with and PS3 can't give it the sales it'll need. If you add in the 360, it may turn a small profit. I'm very excited for this, so there's hopefuly thinking in this also. 60% chance since Guilty Gear Isuka never made it to Xbox and because Guilty Gear 2 Overture isn't coming to PS3.
I think that's about it.