PlayStation Network delivers the goods

The good news is that you can download each PSP game you buy to five PSPs. Transferring a game to PSP leaves a new Certificate Utility in your Game menu, registering that PSP as "one of your five." It’s a shame that if you want to load the game on to more PSPs you have to download it from the Store each time (the file isn’t stored on your PS3) but you could- conceivably- put the game on all your friends’ PSPs for free.