MacPost exposed a photo appears to be the back plate of Apple’s iPhone N94 prototype. This "N94" is speculated as a part number of iPhong 5 or an updated iPhone 4 or iPhone 4S.
The codename ‘N94′ marked on cover clearly indicates that it is a fifth-generation iPhone part. The front cover, however, is labeled “EVT2″ (Engineering Verification Testing) with date ’07-June-2011′, marking it as early development prototype.
Code references to N93 and N94 were discovered a while ago by 9to5Mac, and seen in the wild (and on T-Mobile) by BGR and while MacCast ascribes them to perhaps GSM and CDMA variants of iPhone 5, it might be too early to tell at this point. However, if these represent iPhone 5, they’re a far more conservative update than recent case leaks, and renders commissioned by MacRumors would have suggested.
We also heard previously that Apple has a lower-end budget iPhone or iPhone nano ready to go for this year, making the mix even harder to predict than usual.