Android doesn't offer full multi-tasking either.
http://developer.android.com/guide/topics/fundamentals.html
Quoted:
On Android, apps are suspended when they are no longer visible to the user. Suspended means the app is still in memory, but it is frozen.
No processing or event handling happens. If the system needs additional memory, the least-frequently used apps that are suspended (in the background) have their state saved to persistent storage and are then killed, freeing up their memory. To the user though, those apps still appear to be in the background. When they are brought to the foreground to be used again, they are restarted and passed an object containing their last state so they can be restored to look exactly as the user left them.
If an app requires processing while in the background, then it must also have a service component. A service on Android is like
a separate small application that runs without a user interface in the background (though not actually a separate application). The service has a server/client relationship with the app. It performs whatever action an app needs it to continue performing should the app be suspended. For example, the service might handle all uploading, so if an app is placed in the background while an upload is in progress, the upload continues. Or, like Pandora, the service might handle all network streaming and audio output with the app only acting as the front-end controls. Unlike apps, services are not suspended or killed (except in extreme low-memory conditions).