PlayStation 3 can't do cross-game chat due to memory restrictions

One feature requested often from PlayStation 3 users is cross-game voice chat, which would allow anyone to talk to friends regardless of which games they're playing at the moment. Unfortunately, cross-game chat can never be implemented due to how PS3s handle memory. 

Once a game is booted on a PS3, the console's memory is mostly reserved for that game until you stop playing. There also isn't enough memory left over to do many other tasks, which is why you have to quit playing a game beforehand if you want to look around in the PlayStation Store or use the internet browser. So why can Vita handle cross-game chat? Vita has 512MB of RAM over the PS3's 256MB, giving it plenty of breathing room to handle other tasks while running a game.