Urban Airship is a company that works with developers to power and send out push notifications through the various applications on your iPhone, and it recently announced that the five billionth push notification left the company's servers. The company has been sending push notifications since June 14, 2009 (when they were first opened up to developers by Apple in iOS), and it's now sending out 19 million push notifications a day. That's notes from games, to-do apps, Twitter apps, and all of the other various reasons that all of your apps have to pop that little window up.
Urban Airship isn't the only company sending these things either -- there are many more notifications going out, through
