So I'm going to assume this ultimately a way to prop up windows phones by making it much easier for developers to put something on the windows store. What surprising (to me) is that they didn't go the Android route given it's open source to begin with, and they already have patent licenses in place.
This makes me think of the ol' OS/2 downfall. OS/2 could run Windows applications; this meant no-one developed specifically for OS/2, so they never got the developer mindshare, so there were no OS/2 killer apps, so users saw no benefit to using OS/2 over Windows.
But OS/2 wasn't hardware. If Microsoft can sell phones that match features, speed, ram, look good, etc but can also run all the apps you want, then that's a more competitive situation than running a significant subset of apps out there (just look at their marketshare which is pathetic for a company with all their resources).
The other two are for web apps, and legacy win32 apps.
They all take different apporaches. So this one for iOS is a recompile and modify approach, Android is more of an Android SubSystem within the OS approach (like the old Unix subsystem that they had)
