If you read my sentence, it was merely stating the advantage I didn't say push is a superset of multitasking. The battery saving is no bs btw, try installing 'backgrounder' (available from cydia) which lets the iphone multitask, and watch the battery plummets.

BUT, it is useful for a class of apps that is better run off of your device: Filtered RSS/Twitter/Database app that alerts you when a certain conditions are met.