I have been addicted to Apple’s Push Notification Service ever since I bought Prowl. There are endless possibilities on what you can do with Push Notifications.
The Apple Push Notification Service is a mobile service created by Apple Inc. that was released with iPhone OS 3.0 on the 17th June 2009. It uses push technology through a constantly-open IP connection to forward notifications from the servers of third party applications to the iPhone or iPod Touch; such notifications may include badges, sounds or custom text alerts.
In the thread, Gmail + push on iPhone w/ Prowl on xSellize forums, crimsontwo gave instructions on how to run the Prowl python script on your iphone. The downside to it is that if your iPhone connection change from EDGE to 3G or 3G to Wifi or any vice versa, the script will be disconnected from Gmail. To solve this problem, he recommends you to upload the script to your own web server instead.