I have both consoles.
When it comes to online functionality the xbox wins in all departments.
Not only does microsoft use the online fee's to get the lastest software sooner, the xbox users also get them about £2 or £3 cheaper.
Also, if you are unsure of a game you can gaurantee there will be a demo 3 to 4weeks before release on xbox live.
Ps3......well the uncharted 2 demo was released 4 months after the game.
Also, playing games online using xbox's payed service the connection is always top notch. No lag or any of that rubbish
Ps3....borrowed AVP of a mate and I have yet to have a game online due to weak connection.

So with all this release date malarky, its like the old saying, "you get what you pay for". ( which now that think it about it doesnt really work, seeing as ps3's we're around £170 more than xbox360's )