I've always debated this...and frankly on a smartphone, a tablet or even a Galaxy Note, we shouldn't have a need to see two applications concurrently. But I think it would make a lot complex things much more practical.

Onscreen's approach was also good, but I didn't quite like it. I think the screen should have 3 modes: Portrait (one app), Landscape (one app), and Landscape (side by side, two apps). Having 3 available was sometimes counter-productive.

And I wish the ICS navi-buttons would be permanently fixed on the screen. Sometimes your playing an app and it disappears, you want to open another app but the only way to escape is to hit the sleep and wake the device. Happened to me a couple times too much, and its annoying as fvck, it proves Android has no multitasking ability. And getting rid of the Menu button was the biggest mistake Google has made in the last 2 years, its a disaster by a design and a functionality standpoint