Sony has taken PSP game Everybody's Tennis down from the PSN store following reports that the Vita-compatible release allows pirates access to the console through an exploit.
MotorStorm Arctic Edge was also recently removed from the store, prompting speculation that it was for the same reasons.
As pointed out by homebrew blogger W.Ololo, however, the authors of the hack claim that it only allows users to run homebrew games and cannot be used to play pirated PSP or Vita releases.