the main difference with the PSP is that firmwares get cracked and exploits are found (GTA for example), but the problem is taking the console back to firmware 1.5, on later firmwares it could be done, but with 2.5 and above you cant downgrade the firmware and even if that gets solved by crackers then sony will just get software companies to bundle a newer firmware and force you to upgrade the firmware back...
... so you have a choice (as my downgrading buddie did), play "some" first gen games via ISO on memstick or upgrade back to newer firmware to play the new game he bought!
a brilliant anti-piracy method, yes, i grant you that it has been cracked but as with the v2.5fw it has taken ages for it to be cracked (and a very messy crack procedure it is) and even then they bought out v2.6fw before the crack for v2.5fw was finished...
oh and v3.00fw is out pretty soon... lol
for me that is a great way to stop piracy along with the fact that downgrading can *brick* your PSP!!!
so sony, i salute you!