PlayStation Vita emulators
Emulators
THERE ARE CURRENTLY NO EMULATORS FOR THIS DEVICE. ANY YOUTUBE VIDEOS CLAIMING TO OFFER THEM ARE SCAMS!
The RPCS3 developers have a small side project for Vita emulation, but it can only display a simple 'Hello world' and run a basic atomic test sample.[1]
Emulation issues
Lack of PS Vita emulation is mainly due to the fact that the hardware has yet to be documented. The console was recently hacked, however, so documentation should start soon.
The PS Vita's PSP part can still be hacked, but none of the existing exploits so far allow for anything useful on the PS Vita side.