In a general sense, this is natural design evolution - where Darwin's mutation and natural selection concepts can be applied (generally) to the evolution and advancement of good/effective design.

The windows phone likely took some of its design concepts from previous iOS and Android designs, and now iOS7 is 'evolving' the same way.

This (evolution) can be described as a recursive process: keep the things that work (natural selection), try something new (mutate) with the things that didn't work.

I would also like to note that I find iOS7's weather app design closely resembles Yahoo's weather app, more so than the Windows' phone.