Engadget points to a new video posted on Vietnamese site Tinhte.vn apparently claiming to show a white iPhone 4 running a "test version" of iOS offering Expose-like multitasking that allows users to select running apps from a grid of nine screenshot thumbnails.
You can tap on a window to expand it (replete with animation) to fill the screen or long-press on it to bring up the familiar "x" button for shutting it down. This is all accompanied by a new "Search iPhone" dialog at the very top, which sends you into Spotlight search that looks very much the way it currently does (though it seems to no longer be accessible with a left swipe from the first homescreen as on previous versions of iOS).
While the apparently all-white home button and a passing similarity of the multitasking feature to the jailbreak tool multifl0w suggest that this could simply be a customized iPhone 4 running jailbreak software.
But a second video posted to the same YouTube account and noticed by 9 to 5 Mac offers more detail of what may in fact be a prototype iPhone. The device in the second video may be different than the one in the first video, as the second one seems to have a more standard white home button with black square inside.
The second video clearly shows an "XX GB" marking on the back along with a number of "X" placeholders in model identifiers, common for prototype devices. A walkthrough of the "About" screen in iOS shows, however, that the model carries 64 GB of storage.
Interestingly, a partial glimpse of the iOS build number can be seen as the "About" screen is shown, and the device appears to be running iOS 4.0 with a build number beginning with 8A as would be expected. Consequently, this does appear to be a test version of iOS 4.0 rather than an upcoming iOS 5 build, although Apple could of course choose to implement some of these features in future iOS releases.
The device also appears to contain several preloaded applications internally used by Apple for diagnostics, testing, and demoing, lending additional legitimacy to the claims.
Update: Noted jailbreaker/hacker @chronic reports that the build is indeed iOS 4.0 8A216. The public release of iOS 4.0 was build 8A293.
