Most folks will say that's actual serial tasking, not true multi-tasking since once you switch away from an application (mail, certain background running tasks excluded though) like that game in the video, it's "paused" and set to resume when you pull it into focus.

That's serial tasking. There's background services; but that's in all of the current Mobile OS out now. Multi-tasking isn't in all of the Mobile OS's out now though, not in a classical definition.