Lewis Carr explains how he turned his Moodle site into a nice layout and format for the iPhone without having to change the core theme. Take a look at his slides showing this.

His hack is for his site only and would be useless to just copy and paste in yours. He replies to a comment:

The stylesheet I use is a modified CSS of my current theme, it would be useless for any other theme.  The hack relies on you modifiying your existing css to add the code.  However, I am createing a stand-alone iPhone theme to work on.. -Read more

Lewis Carr has many great Moodle developments, check out his (best I’ve ever seen) http://moodle.parklane.ac.uk/. You can also  follow him on Twitter or take a look at his site.