I think you are confusing the O/S with the application. Android does support multi-tasking, but most of your issues seem to be that the default web browser doesn't multi-task. That's a problem with the web browser, not the O/S.

If you download from the Android marketplace you can switch away and the download will continue in the background. If you want to listen to the radio then find a media playing application that will continue to play.

It is true however that multi-tasking on Android is different than on your n900: by default applications don't continue to run in the background. The O/S will tell an app when you switch away, and most apps will just save their state at that point and stop doing anything. The app then usually remains in memory unless you are running low on memory and when you switch back to it you should be at exactly the same point.

When you switch back to an app via the home key it usually will have been running and will come back exactly as you left it (and more quickly than restarting). Unfortunately some apps (I'm guessing maybe ported from the iPhone) don't work if you switch back and just crash instead.

For an application to do something useful in the background it generally has to be written to provide a background service otherwise it is in danger of being killed because the O/S thinks apps which aren't foregrounded are fair game. But that's down to the developer of the app: if they thought it would be useful to continue downloading a web page the browser could do that, but the thinking was that it might impact the performance of other apps so most apps don't do anything while in the background.

Edit to add link to this description of Android multi-tasking: http://android-developers.blogspot.c...droid-way.html