Although iOS does many things really well, its multitasking UI is not one of them. The iPad's gesture support makes things much better, but on the iPhone, it's just clunky. As it just so happens, Apple has brought on someone with a few ideas on how to improve that.
Earlier this year, Jan-Michael Cart made a few concept videos for new multitasking and notification systems in iOS. It involved faster app switching and app closing, among other things. According to 9to5mac, the Cupertino company has snatched Cart up as an intern, which means they must have been impressed by something.
Obviously, some aspects of the concepts aren't ideal, but if they keep Cart as a full-time employee, I'd love to see parts them baked into iOS. [9to5mac]