Looks like PSVita Hackers have been busy and released the PFS Keys for the PSVita, heres more info:
The PS Vita PFS keys have been posted in the HENkaku wiki (mirror) by St4rk. So what are the PFS keys? Quote Yifan Lu: 'The second layer of encryption is PFS. All game data (images, textures, executables, etc) are encrypted with PFS. PFS key is derived from a passphrase chosen by the developer. This layer is decrypted when a game is mounted.' Thanks goes to Joonie for the heads up."