Unrelated to WebOS, but the Pre's wireless charging accessory is IMHO still the best to date.
On the MeeGo OS used on the Nokia N9, it requires swiping in one direction a couple of times to get to the open tasks screen. You can then press and hold on the screen to allow for closing any app(s) you want and click on the done button after you're finished.
Closing an app requires just swiping from the top to the bottom. IIRC, WebOS required you to swipe upward to get to the task screen and then swipe upward again to close the app.
I much prefer WebOS's approach. On the other hand, in those days you wouldn't really have more than a few apps open at once, unlike iPads which could have dozens of apps or browser tabs. So who knows if WebOS's style would translate well to today's usage patterns.