The renderings use Hajek's past budget iPhone concepts as the basis for the hardware. As for the software, he incorporated a round of nice concepts by 3D artist Dámaso Benítez, picturing a flattened iOS 7 user interface that Apple's design head Jony Ive and his team are widely believed to be working on.
His mockups, Hajek explains on his personal blog, serve to illustrate "how Apple might introduce the new, cheap iPhone." More awesomeness can be found right past the fold...