Andronicus said:
Can Steam actually be used for anything other than playing Portal 2 on the PS3? I don't understand exactly what you can do with the service.
At the moment, as far as I know, no. But don't forget that all the new Valve games will be using it - CS:GO, HL3 etc. Maybe even some third-party developers will jump on it.
As for the service, it provides THE CLOUD, allowing you to store your saves on Valve's servers, and cross-platform gameplay, PS3-PC-MAC, allows you to chat with your PS3-PC-MAC friends. That's pretty much it for now.