The PSX4Droid app has become the latest retro emulator to arrive on Android mobiles, bringing the back catalogue of Sony's original PlayStation to Google's phones for the far from ruinous price of £4.
See the Android phone PSX4Droid in action in the clip below
Like any PlayStation emulator you will need to get hold of the PS BIOS file and the various ROMs which contain the game data and this always comes with the problem of copyright infringement, unless you happen to own the original copies of the games which you are intending to play.
A YouTube video of PSX4Droid shows it running games at solid frame rates and with all of the controller buttons transposed onscreen for touchscreen interactions.
Sadly it looks like the analogue sticks are not available, which could make playing the later titles less than ideal and the non-widescreen resolution of most PlayStation titles is accentuated with letterboxing, but otherwise it is a fully featured, well put together emulator.