Video has surfaced of a prototype PlayStation Vita, featuring a sliding face reminiscent of the PSP Go line of handhelds and a means of using generic memory cards. You can get a look at it, operating what appears to be a prototype of the PS Vita firmware, in the video by AssemblerGames above.
This is not the first time PS Vita prototype specimens have been seen in the wild. As this thread in AssemblerGames' forums points out, some 100 were said to have been produced before Sony arrived at the handheld's final design. All were supposed to have been destroyed but, of course, it never ends up that way. One prototype was said to be sold two years ago for $700.
In the video, one can see the sliding face revealing the PS Vita controls — two analog sticks, the four face buttons and a D-pad, albeit in a different orientation. With the front collapsed, the device appears to be on the whole smaller than the current PS Vita, the protrusion from the bottom notwithstanding. (It's unclear if that is a prototype peripheral, an attachment used in development only, or something else.)
The PSP Go was introduced in October 2009 and discontinued two years later. It featured a sliding face, one analog stick control, and could only use digital media. It was intended as an alternative to the PlayStation Portable (then in its 3000 series) and not a replacement for it, but shelved as Sony turned its development interest toward what would become the more powerful PS Vita, with more features, and greater interoperability with PlayStation consoles.