Over the past few weeks, hackers from Wololo.net claimed to have exploited code found in two downloadable PSP games to essentially crack the PlayStation Vita wide open, allowing for the playing of pirated/homebrew games on the system.
Those two games were Everybody's Tennis and MotorStorm: Arctic Edge, the latter of which was shown off with a hacker playing the PC version of Doom on Sony's new handheld. The Wololo hackers claim the exploits would only be able to run homebrew games and not pirated PSP or Vita titles, but it appears the platform holder isn't taking any chances.
Sony has now pulled both games from the PlayStation Store, and pulled them good: even if you've legitimately purchased the games previously, they're now no longer available for download.
It may all be for naught though, as the hackers claim that tools for making the most of the exploit are already done, and in the hands of thousands of users.