The iPhone has fake multi-tasking.
Android has a fake-limited (hybrid) type of multi-tasking (ie better than iphone).

I find the multi-tasking on Android to be insufficient most of the times, and the period where my Galaxy S must wait to kick start the App (eg browser) is considerable for something that is supposed to be mobile.
Also Android randomly kills open Apps without your consent, and this becomes increasingly annoying (I almost bricked mine by throwing it at a wall).

The N900 is very very good at power management compared to Galaxy S/Android ... so I believe the N900 has the best compromise of "power management"/"multi-tasking" ratio (better than the iPhone), trully.

I want each Apps to be active in the background (multi-task) when I go to the Home Screen, however if I select to kill them, then they should be killed (not automated like Android), so then I can literally take control of multi-tasking and thus use it tailored for my needs (and power consumption).

This isn't rocket science, but only Maemo 5 has got it right and I hope this feature makes its way to MeeGo