Apple is said to be planning some major updates for the iPad with iOS 9, including a split-screen app mode, which was also rumored to be coming last year with iOS 8.
Along with other features planned for iOS 9, Apple may be planning some significant, iPad-only features for this year. While first reported to be coming as part of iOS 8, the iPad may be getting a side-by-side app mode, which would allow multiple apps to be displayed at the same time. However, the mode may also allow users to open multiple views of the same app side by side as well, according to 9to5Mac:
Sources now say that Apple plans to show off the side-by-side feature for iOS 9 using currently available iPad models. The latest plans suggest that the split-screen mode will support 1/2, 1/3, and 2/3 views depending on the apps. When split, the screen can either display two different apps side-by-side, or multiple views of the same app. This would enable iPad users to see two separate Safari tabs, or compare a pair of Pages documents at the same time.
Apple is also said to indeed be planning two models of the rumored iPad Pro, presumably the Wi-Fi-only and cellular models. The split-screen mode, though thought to work with current iPad, was apparently originally developed for this device, and Apple is reportedly looking at optimizing iOS even further for the larger screen:
While current "iPad Pro" prototypes are said to run a version of iOS that looks like a larger variant of the iPad mini and iPad Air version, Apple's goal is to further tweak iOS for the bigger iPad so users can better leverage the additional screen real estate. Besides split-screen apps, Apple is considering redesigning core apps and features, including Siri and Notification Center, to be better presented on the larger display.
Also reportedly in testing is support for multiple users on the iPad, which, much as it does on the Mac, would allow users to create separate partitions for themselves on a single iPad. This feature has apparently taken a back seat to other iPad improvements, and may not in fact ship this year.