iPhone is most popular camera phone on Flickr - The Unofficial Apple Weblog (TUAW):
While we're on the subject, I'll offer my tip for taking decent iPhone photos. Unlike nearly every other camera ever made, the iPhone exposes an image when the "shutter button" is released, not depressed. With that in mind, here's the three step process I follow
1. Press and hold the "shutter button"
2. Compose the shot
The tendency is to compose the shot and then tap the button, often resulting in blur. Try this method and watch the results.