Since we are paying yearly for these subscriptions for both console. Both of the company should implement a new SERVER for the paid subscriber so they can have matches like Super Street Fighter 4, or any other Fighting Games, FPS, or any Racing Games etc via PS3 vs Xbox 360.
By doing this. Many people that were hesitant or doesn't like the idea of a paid service would think otherwise. That they can finally battle it out with their favorite console against the competition. I think its a great idea, because I for one would like to pay the service, just to have a more variety of players to battle with. Especially with the other system.
Since its not the server from Sony or Microsoft. Maybe the game developers can work something out with them. Offer them a little bit of something so all 3 company will gained something out of it. That way it would have more people willing to pay for the service.