Yes you can, think about it. The reason why everyone says no is because there is nothing that tells us how to do it, if xbox told you how to do this then what would be the point in you paying xbox live, you could just use your xbox and play on ps3 network. No isn't an answer, there is always a way.
Not yet, but developers may incorporate this feature into games in the coming years.
No.
it cant be done
yes
no
It's where you and friends or random people, play online together and you can send messages and also talk to them with a mic.
Yes, but you will need a xbox360 live gold membership card to be able to play them online.
COD4 is the slang name for Call of Duty 4. According to my source you can play online with an Xbox 360. There's some discussion and debate on whether the game is better played with an Xbox or a PC.
no
You can not play two players online on cod4, it is one player only, the only things you can do with two players is split screen. You could make another user on your ps3 and let one person play on that account and another on a different account
No. The networks are separate.
no but i wish you could =)
go online
yes, there is a 16 player online for CoD4 for 360, ps3, and PC