Calling All Cars! not only with friends but complete strangers.
What it amounted to was a strange rental system, since players could share the same game with up to five PlayStations, and actually deactivate the game from one account so it could be registered with a new account. The possibilities for exploitation were endless.
Sony America has changed that policy. Now, players can only share with two activated PlayStation 3 systems. While once again a PS3 could be deactivated for a game and reactivated on a new system, just having two systems to do it with makes it more stringent.
Some PS3 users will be happy to know that the policy is grandfathered - that is, the old policy will apply towards content purchased up through 17th November. From the 18th on, the new policy will be in effect.
Sony Europe has not adopted the policy yet, but it's reasonable to think they'll follow suit as well.