Why do you have to display them at the same time? Even my desktop pc doesn't allow me to have two mouse pointers and use both apps at the same time with both my left and right hand. (hmm, maybe it does? lol. Haven't tried)

btw, N900 does that while in the task switcher anyways. Also, displaying multiple "interactive" widgets on the desktop showing me different live feeds means it's true multi-tasking according to your theory.