So a friend of mine tells me he asked a relative who works in Activision to get him a copy of MGS4 since the guy can get games a good few weeks before general release.
The guy replies "Do you want the PS3 version or the Xbox 360 version.. I'd go for the Xbox 360 version because it looks a lot better on the Xbox".
Now this means either (a) the activision guy don't know shit about games and should be fired for using excess bullshit to cover up his ignorance or (b) he know something we don't.

Is there any viable evidence out there, something more than rumours?

It goes something like this

Playstation 3 is next Sega Saturn
PS3 overpriced.
Sony losing money hand over fist in selling PS3
Movie Moguls Dump Blu-Ray
PS3 game dev learning curve virtually impossible
Cell archaic architecture and full of bottlenecks
40% Belgium PS3's crash
Dust voids PS3 warranty
PS3 frame rate pile of shite
PS3 graphics even more shite
PS3 eats gigawatt's of electricity in standby
Microsoft (there, I said it) buying out developer studios and game exclusives faster than rainforests disappearing.
PS3 gamers slashing wrists on hearing that Bioshock comfy in monogamous relationship with 360 thank you very much.
Another PS3 exclusive collapses - "Intergalactic Space Onion Circus" now available on all platforms including microwave and subway ticket dispenser
Teenage mother denies stuffing baby into PS3. Mother aged 16 states "I spent all my welfare on this M*&^%$£ FU&%&ing machine and there are no decent games. One minute the baby was sitting there, then next - I don't know. I think I blanked out. It ate my baby"

Y'know
I dont give a flying monkeys about bioshock.
Nor do a lot of other people