We've mentioned this in passing before, but the parallels, if any, are worth making more prominent.

Using webOS, which is a localized, almost widget-ized development environment (using HTML, CSS, JavaScript, and enhanced local access), the Palm Pre can run many WebApps at the same time. The way it's visualized is with the "card" metaphor, where a touch of the Home-like button shrinks the current screen down to a thumbnail that's kept live and updated in real time. The interface also lets users shuffle the apps like cards in a fanned-out deck. You re-arrange the cards and can even terminate an app by "throwing it away".

While the iPhone doesn't keep them live or let you re-arrange them, and has an X to close rather than the throw-away gesture, going as far back as two years ago when Steve Jobs introduced it at Macworld 2007, it let you zoom out of the Mobile Safari web browser with an eerily similar thumbnail representation. (Though there doesn't seem to be any patent contention over that just yet...)

Actually, given Apple's recent obsession with Cover Flow in iTunes, OS X 10.5 Leopard's Finder and now Safari 4 Beta, we're surprised they didn't just default to that for Mobile Safari tabs from the get go as well...