The amount of copies of a particular movie or game that are pirated are related to how many it will sell. If a game is really popular, more people will buy it and more people will pirate it. The only game that had a disproportionate amount of pirated copies was Spore, because everybody was pirating it to protest the DRM. I highly doubt PSP games are being pirated any more than DS games, and if anything, they're being pirated far less because you actually have to mod/hack firmware/whatever. Downloading DS games is as easy as downloading .mp3s. There are still a great many people who will never download DS games or .mp3s.
I don't think piracy really hurts Sony or Nintendo though as much as they say though. I think it gets them to sell more hardware, DOESN'T hurt game sales (I think if forced to choose between paying or not playing, they'd choose to not play), and actually raises awareness about their games. There are pirates with tons of games, and their friends come over to play stuff. Their friends go "Wow this is cool can I borrow it?" and then "Oh, it won't play on my system at home unless I mod it?" "Naw, I don't want to mod it, that sounds risky. I'll just buy it."
I'm not advocating piracy, but I think video games cost too much, and if they can get the prices to a point that more people are comfortable paying, then the increase in sales will more than make up for it. Some people will always be pirates, and some people will never be pirates. And there are some who will only pirate if something costs waaaaay too much or is riddled with DRM.












