The question is that Android places new alerts in the system wide notification bar while the iPhone places a notification directly over the specific app icon.
So wh
Though it might be possible to do such a thing it is absolutely not recommended to try and change the app's icon. This behaviour originates from iOS and is not used on Android at all.
You can create a widget that shows the unread count and takes the user to your app if the widget is clicked though. The Google Reader Android app offers a good example for that:
