Running apps from one mobile platform on another is theoretically great for boosting your app selection, but it's not a trivial task -- even BlackBerry's Android support is rough. However, some Columbia University students have managed the daunting feat of running iOS apps on Android with their Cider compatibility layer. This isn't a regular emulator or virtual machine, like you might expect. Instead, it simply tricks apps into believing that they're in a native environment: they adapt code on the fly to make it work with Android's kernel and programming libraries. Even 3D benchmarks run properly.
Unfortunately, it's not quite the Holy Grail of cross-platform compatibility... at least, not yet. As you'll see in the (sadly vertical) demo below, most iOS apps run at glacially slow pace. They also don't have access to most hardware features, so GPS tracking and other staple features are right out. This is still better than previous efforts, though, and it raises hopes that platform exclusives won't be as important in choosing a mobile device as they have been in the past.
Update: the team tells us that it got GPS working after the paper was published.