OK, this isn't webos, it's Gnome 3, but they've essentially done what WebOS on a desktop would be and it's fantastic!

They even have "Just Type" (they call it "Type to Search"), non-intrusive and interactive alerts at the bottom of the screen, etc. They also made "workspaces" which are basically like Firefox 4's TabCandy/Panorama/TabGroups. Sort of a re-imagination of card stacking for a desktop!

GNOME 3 - Made of Easy