Since the arrival of Apple's iPhone back in 2007, the world of mobile design has never been the same. Gone are the days of designing everything extremely small, highly compressed, and generally not very well. Now we have apps, designing for mobile is a new, and relatively easy process.
After a brief scour of Google, I found some interesting articles, namely a study showing how people actually interact with the iPhone and touch screen devices. As a designer or developer, it's easy to assume that everyone knows how to use and interact with these devices. Research shows however, that users are actually quite slow when first using an iPhone, and interaction was not at all consistent throughout the provided applications installed on an iPhone.
With the introduction of iOS 4 - most of these issues have now actually been ironed out. Apple have now provided a decent interface, and with various tutorials and articles online, it's fairly easy to start mapping out your application.