PS3 DRM: Downloads support five systems
Games bought through the PlayStation Store will be able to run on five-or-fewer systems. Of course, if you own more than five systems, you can probably afford to pay for the game again on the sixth. (Hah, we kid; you didn't get so rich by wasting money on a game you already bought.) The important application for the five-or-less rule is that you can log in to the PlayStation Store at a friend's house and re-download a game for free.
When you leave your friend's house, Sony says that you can leave the game there. If the title is an online multiplayer game, only one of you can use it at a time. But if it's an offline game, we were told that the multiple systems can continue to play it.
Sounds like you and your four best friends may be splitting PS3 game downloads.
See also: Share XBLA games on two Xbox 360s... legally
