There is a really interesting experiment that you can follow day by day in the web: following a new iPhone app creation from the initial concept up to the final code and Apple store submission.
The app is called “Dayta” and the author is Sahil Lavingia.
The app will be created from scratch, all graphics will be custom (a part a few icons) and it’s also quite useful.

You can follow Dayta creation with the blog or twitter.

And if own an iPhone or iPod you can ask Sahil to be a beta tester. We are doing it too…