There is already an open-sourced project called E-skimo which includes such component. It is tested in mobile, and in fact it was developed to give Flex components more native look back then. The component is called SectionList.
https://github.com/People-in-action/eskimo/blob/master/piaMobileLib/src/main /flex/com/pialabs/eskimo/components/SectionList.as The github project also includes a mobile demo which shows of a few other components. Tangent
