Microsoft and Sony is trying to combined Xbox 360 live and Play station 3 live together in 1 server. It will be happening in a few months now maybe because of the Play Station 3 servers are really lag so they want to get rid of them and just us Xbox live servers.
For the Game play, If you have a xbox 360 and your playing a game like Two Worlds or MW2, You will beable to play with a person on the Play Station 3 even tho your playing on the Xbox 360. Your friends list will beable to have 360 players and PS3 players. They are having problems sorting it out because its not compatible yet and it will be like a 1 GIG Patch probably.
The games that they are going to be making now are going to be for Xbox 360 and Play Station 3, Unfortanlly the games that they already are out will not be going anywhere, Like Halo 3, Its only still going to be for Halo 3. They are going to be making Real Time Strategy games for Play Station 3 probably, im not sure there is some already.
I will keep you guys updated on what is going on with it.