So I was looking over the patent Palm filed for multi-tasking using the card metaphor. Cool part about that is that stacks have been a idea from the start (Apr 2009) but the patent also cover something called Grid mode.
Basically grid mode calls for grids of 4 and 9 visible apps/cards and a 16 card grid with scrolling.
pics of the patent attached.
I think this would be awesome for our future PalmPad.