Correction
To quote: "This summer sees iPhone OS 4.0 released, with enhanced multitasking in seven areas, but it's closer to the notifications system of OS 3.0 than the pre-emptive multitasking a computer science course would define."
This is completely wrong. The iPhone has (and always has had) pre-emptive multitasking as it would be defined in a comp sci course. Just because the App Store usage policy hasn't allowed it doesn't make it not there.