Chase Jarvis is known for popularizing the idea in the mid-00s that the iPhone should be taken seriously by professional photographers as a camera. His point was that the technology of any camera was really just a set of tools to help you uncover a story or insight, and that process was better served by the access and habit of mobile photography than the sporadic and specialized availability of a D-SLR.
From the intro to his book:
I hope to underscore—perhaps help legitimize— the idea that an image can come from any camera, even a mobile phone. Inherently, we all know that an image isn’t measured by its resolution, dynamic range, or anything technical. It’s measured by the simple—sometimes profound, other times absurd or humorous or whimsical—effect that it can have upon us. If you can see it, it can move you.
For me, the iPhone has been a dream come true. One button. Always with me. Incredibly accessible. There’s no losing sight of the work at hand by way of more complicated gear. Writers have notepads, painters have sketchbooks, and I have a camera that’s always with me. Chances are, you do, too.
If we allow it, photography can escape the technical trappings of so many other artistic endeavors. It’s accessible, nearly ubiquitous today. And it’s given us an opportunity— more than ever before in history—to capture moments and share them with our friends, families, loved ones, or the world at the press of a button. It’s the moment. The little snippet of life unfolding in front of your lens—whether that be glass, plastic, or a pinhole in a cardboard box. As an artist, I feel more free with the little camera built into my iPhone than I ever have with any other camera. I somehow recovered an innocence I’d lost, and I was able to see the world again for what it is: a beautiful, funny, sad, honest, simple, bizarre, and wonderful place.
If taking pictures helps you see this, then keep shooting. The best camera is the one that’s with you. (Source)
Many people think that the cameraphone’s ubiquity kille the compact digital camera market. Analyst Heino Hibig disagrees. See Camera Bump-Down