[Matt] over at Make came up with a way to send push alerts to his iPhone whenever his mailbox is opened.
The electronics are just a switch mounted to the mailbox connected to an Arduino with an ethernet shield, but the interesting part of the build is the code. [Matt] got the Arduino WebClient to request a PHP script sitting on a server. This script connects to the Prowl API to push the notification onto an iPhone.
[Matt]‘s project has been up for a few months now, and we still haven’t seen any projects using an Arduino+Push combo, or really any other phone except for the iPhone. We think this could be done on an Android phone with cloud to device messaging, but that can’t be the only solution. Any hackaday readers have an idea of how to implement this outside the iOS world? What would Hackaday readers do with a microcontroller that can send push alerts to your phone?

http://hackaday.com/2011/04/15/push-...-on-an-iphone/