I love the Palm Pre's UI. Lots of it is original and revolutionary on a mobile, but some feels borrowed from desktops. Which somehow makes it an amazing phone.
Through out the presentation, I couldn't help but admire how great it is at multitasking.
1. Of course, there are the now-found-everywhere swipe gestures.
2. But the app switcher looks and feels like a cross between OS X's Expose and Spaces window and desktop managers, a bit.
3. There's also a universal search function, which is like OS X's spotlight.
4. They've gone to great lengths to make sure that incoming messages and calls don't kick you out of your current task, much like they don't on almost any desktop computer. Most phones interrupt your task immediately when a call or SMS comes in, with at least a top layer pop up, if not an entirely new screen.
5. Both the static doc and the wave bar are extremely similar to OS X's dock, which can be hidden and zoom variably on different icons.
6. The calendar's UI is exactly the same as a desktop client like, say, iCal, or even a web based client which uses color to show different datasets.
In these ways, I think the Pre and its web UI have done an amazing job of advancing the state of the art of handheld user interface. Strange that so much of it was borrowed and repurposed from the desktop.