Emulation and achivement system.

the emulator will probably emulate the psn connection too, to fool the games into thinking it's connected and authorized. it won't actually be, and everything will probably be stored somewhere in the emulator's profiles or saves.

It isn't that easy to do that as most people tend to think. And it's not part of the purpose of an emulator, this goes far beyond accurately emulating the hardware. It would involve some serious hacking and cracking.
Imagine that all of Sony's anti-piracy protection is designed not to let games think they are connected if they're not.