This video shows a Schogini Systems Iphone app that allows you to simulate Arduino circuit breadboarding and sketch coding on an Iphone. According to the video, you can email the code to your computer for further development or device programming.
We couldn’t find it in the app store yet this morning, but this concept looks promising.

An Arduino simulator that runs on the iPhone – PERFECT! These two belong together…
The “only” minus in this app is the fact that you can only tweak minor stuff in sample codes and not write anything by yourself. :/