The iPad has only ever been able to show one app on-screen at a time, but that might change in the future. In a beta version of iOS 8, developer Steve Troughton-Smith has discovered that the operating system supports resizing apps so that a single app might only take up three-quarters, one-half, or one-quarter of the screen. In a video, Troughton-Smith shows exactly how it works right now inside of Apple's desktop iOS simulator, using two-finger swipes to drag an app into a smaller and smaller portion of the screen.
It's not known when this might make it make it to the iPad
The animation doesn't look beautiful yet — it isn't finished, after all — but the app scales to some extent to fit the smaller size, so it's clear that Apple's put some work into this. When we'll actually be able to run multiple apps side by side on the iPad remains to be seen, however. 9to5Mac reported earlier in the year that split-screen multitasking was in the works, but warned that it might not ship with iOS 8 — and indeed, it isn't for now. But a portion of the code is clearly there, and if Apple does choose to move ahead with it, it's always possible that we'll see it turn up the next time a new iPad is announced, likely this fall.
Reports have also suggested that Apple will begin pushing developers toward coding apps that can easily and automatically scale to different display sizes. That would make transitioning to bigger phone sizes much easier in the future, and it could also tie into this. Alternatively, developers may simply be asked to create scaled versions of their apps if they want to allow them to work in split screen. Troughton-Smith says that the mode he tested only works in landscape — and not in portrait — though he can't say for certain whether that's Apple's intent or just a bug.