@radphil: Because the actual SDK is incredibly overpriced and it comes with free NDA's.
Why the hell are you all claiming that "hackers" and GeoHot are all there for piracy and cheating? There's no way to "pirate" games from OtherOS. There's also no way to access PSN or play ps3 games from OtherOS. OtherOS doesn't enable "cheating", and it was not ever developed with the intent on piracy.
The thing is, with PSX4droid, considering that it runs PS1 games the makers have long-abandoned the titles, and don't care what you do with them anymore. Also, PSX4droid has nothing to do with rooting, and many people root because of the horrible manufacturer-installed software which nobody likes and you can't remove without hacking the phone. (Motoblur comes to mind, nobody likes it but you can't remove it).