The PS Vita was launched just three days ago in Japan, but there are already reports that the first ever Vita homebrew was run already on the handheld! The reported homebrew, already confirmed by a video posted on Youtube is the popular Hello World exploits.
The thing that made this thing possible, apparently, was the fact that the PlayStation Vita has an integrated PSP emulator that allows it to play PSP games. So from here to making Hollo World work was just a small step.
And as I said, today is a proof that the first homebrew was run on Vita and you can check out the video below:
[source]