These days, Google is looking more and more like Apple's rebellious sibling, constantly flouting the House of Jobs' rules to get their technology and functionality onto the iPhone by fair means or foul. Their latest "hack" (for lack of a better term) lets Gmail users get their new messages pushed to their iPhones automatically.
Mind you, the iPhone does support a native Gmail app, but only with pull technology. (Android and Palm Pre owners already enjoy push tech.) The trick is to set up an account on Microsoft Exchange with your Gmail info, then use Google Sync to sent Gmail messages (as well as contacts and calendar events) straight to your handset. (This article tells you how.)
The only drawback to this trick is that the iPhone only supports one Exchange account; if you have separate Gmail accounts at work and at home, you'll have to decide which one gets The Big Push.