It's not perfect: you'll notice the edges appear a little like an old T.V. blurring out the last inch of viewing - but on a monitor this is a fantastic application for the iPhone that allows you create a piece of art at the flick of the index finger - the multiple brush sizes allow you to create a depth of field by simulating the illusion of texture. My tip would be to follow the contours of the image you start with (close-ups, good contrast work best) - so you would trace back and forth in arcs and curves as you would if you were actually painting the subject - a great application for a great phone that lets you waste a little bit of time by actually flexing your frontal cortex.
Here's another cute picture that translated into a great little digital "painting".
