Google has announced today that they have included push notifications for Gmail on the iPhone and iPod Touch. By making use of Google Sync, iPhone owners using iPhone OS 3.0 and newer will be able to automatically synchronize messages to their phone without intervention, within seconds of being sent an email.
Google is offering the ability to sync contacts and Google Calender entries instantly as well. All of this functionality has been present in Google's iPhone software for some time -- just not with Push. Setting it up easy: If you already use Google Sync, it's just a matter of toggling the setting. Google noted that the always-on nature of Push email would result in heavier power drain -- something to consider if you treasure your battery life.
Although Apple is still against the idea of making the iPhone a multitasking device (for a variety of reasons), they have allowed outside applications to including Push functionality. As software development on the iPhone matures, more programs support some form of Push, which makes an Internet-connected phone all the more interesting to tote around. Hopefully development like this continues to improve on several fronts.