True, this TECHNIQUE is "old skool", it has been available since the early Nokia Symbian devices.

What they have is few specific services for true multi-tasking ability (actually still running), which is also available for Symbian, the calls still works, the music player is part of the services, etc.

Their reason for only allowing specific services is to controlled usage, to control the battery and processing (so, users won't open too much app, thus affecting their slickness/smoothness of the phone).

But the "task switcher" concept is just exactly like Symbian and Windows Mobile. It's nothing new, in fact, it's very old concept; somehow this isn't like Apple, would expect them to come up something unique. But I guess, it's better than nothing for the iPhone users, at least now they have official "backgrounder" built in.