If I'm not wrong, their multitasking only works for 7 specific service.

The iPhone OS4 version is very much like Symbian multi-tasking, hold the MENU button then you can see the list of app. For Symbian, the built in music player is part of the service, calls, sms, all these are running in background, not sure about other service,

It's nothing like the N900 multi-tasking, which is true multitasking and you can see those web page loading, games running, videos playing, etc.