Looks like someone found a way to run PSP homebrews on the PS VITA. Video here. Someone else also found a way to access a test mode, pressing R+PS+Power button? Note that they have not figured out how to exit test mode, so it's not recommended anyone try this. Video here.
Top one probably won't do much. Since the emu is sandboxed. Second one, is it really a test mode someone got into though? Also R+PS+Power is recovery mode on boot. Not sure how it would lead to the test mode (it's a hw production tester that normally gets flushed after the firmware is installed).
For the first video, it would be ok to run userland apps. As for the second video, I can't read Japanese so I was just posting that off the rough translation. How would you exit that mode?
Recovery mode you can just simply reboot. But I really don't think he got to that from recovery mode. I really haven't seen any additional info on how he really got to this or if it came like this.
Don't know but suposetly another PSP hack opened in vita fw 1.51 that let wololo get picodrive PSP running on a vita.