There are only two games that have that for the xbox, Shadowrun and lost planet. but those are old games. i like sony approach there more open

It will make online communities last longer.

wasnt portal 2 a cross platform with PC/PS3

Yes it was 

It would be pretty tricky - would the developers be able to marry the different xbox/ps3/pc hardware into the same games? Seems tough to me - more so for MS to do as they tend to protect their xbox live much harder than sony with psn.

If however it can be implemented then it would be great.

i know right.

Cross platform sounds like a loss of money on one participating company, if not both.

It depends...cross platform is perfectly acceptable for co-op experiences but as far as MP is concerned PC users have a very unfair advantage over console players.

They should do more PC/PS3 steamworks esk cross platform play, too bad competitive online shooters cant happen because of mouse > analog but other genres and simple co-op should be common placed.

on an unrelated note, you know what SONY should release along side there next console, a cut down PS4 that is smaller in size and has no cd drive or HDD, which fits into a PC case and attaches to a motherboard so you can have a console and PC combined into one console which will provide a frame work for a budget gaming pc because the GPU priced ps4 extension can independently run all the games which developers will over time endlessly optimize and get more out of but you also have your PC that doesn't have to have high end ram or cpu to run your games and instead cna be used for other tasks. I dont know why MS or SONY have fought of this, tho i should be asking would anyone buy a console which you can plug into your desktop to run your games instead of having a entirely new box.

I dont see why you cant have the option of only playing against gamers on your particular console i.e. a ps3 gamer having the option of only playing against other ps3 gamers. I dont think this would be hard to set up and im sure that if there is a plan to do this, then this kind of option will be included.

WIll be interested to see how the Eve/Dust crossplatform game crossover works. Im sure at a later date, PC players will get to play Dust 514 (particularly if its a highly reviewed/selling one) and in that case there will clearly be crossover between the pc and ps3 versions of Dust. Will make for a good comparison.