John Gruber’s Talk Show discussion with Dan Frommer about how to implement split screen on iOS got me thinking about how this feature could be implemented. A hint could be in how “Open In…” is currently handled. In the “Open In…” feature, apps register as being capable of handing certain types of files. Likewise, an app could register as being capable of split screen mode. Then, from within an app that has this enabled there would be an icon indicating split screen mode (or possibly another menu item in the share menu) that would bring up a grid of capable apps, again like in the “Open In…” feature. Tap on your choice, and the new app opens opposite the app you’re working in.
One can certainly imagine shortcomings in the approach, but perhaps it’s a start.