there's a lot of 'slightly wrong' or 'mostly right' info on psp gamesharing in this thread, so i'll lay it out clear and concise.
an account can be on up to 5 PS3s. Each of those PS3s can be synched to a different PSP. Therefore, an account can be on maximum ten devices (as long as the psps go through a master ps3 account, since that only counts as 1 usage for psn). Gamesharing works at the account level not at the game level -- that is, all games bought on an account can be played by machines with that account activated.
Now, the biggest difference between gamesharing ps3 and psp is that while you can have 16 accounts on your ps3, you can only have one active account on your psp. So, for example, if you download psp games on different accounts on you'll need to sync up and switch accounts to change what games you can play. This can be a pain, so it's recommended to do all your psp buying on a single account. Best case scenario for a gamesharer, immediately after buying your psp you find a good group of people to buy with.
While a pain to have to switch accounts, it's actually not that difficult and can be done in under a minute if you're near your ps3. You do not need to delete games from your card, you simply can't play them until you reactive the owner account.
on topic -- sadly, i picked up p3p and riveria recently... but just added COH, Hexyz and CGS to my collection thanks to this sale.
And while I do own a 3000, I much prefer digital copies... I love having a huge collection of games available to me without toting around UMDS...
[quote name='marineal']when you buy a digital psp game, how many times can you transfer the game?[/QUOTE]
You can download and install the game as much as you want, forever. The limits are simply on the number of active accounts as explained above. But you can always deactivate on one machine and activate on another, so there is no finite limit to 'transfering' in any, way, shape, or form. The only hard limit is 5 psps at a time, but you can switch those psps by deactivating and activating for eternity. all 5 currently active accounts can play any game owned by that account.