If you ever needed an example of the power of iterative design you need look no further than what the designers of the Convert app for iPhone did with their amazing mobile app.
The tap tap tap team posted a video a while back that plays like a time lapse video of all the iterations the design team went through. It’s amazing to see all the choices they team went through, discarding many and making others integral to the app (see the video below from YouTube).
The recognition by the design team that iteration is a key part of the design process is a testament to the value of the UCD process. This app, which is well worth the 99 cents just for the exposure to the interface, is useful, elegant, and, perhaps most importantly, fun to use. But it should be, it’s the product of continual refinement of a great idea.