BBC News has shown how straightforward it is to create a malicious application for a smartphone. Over a few weeks, the BBC put together a crude game for a smartphone that also spied on the owner of the handset.
The application was built using standard parts from the software toolkits that developers use to create programs for handsets.
More here including a video with Bloor Research adding some commentary. This project took a few weeks but it has been very interesting—happy to talk through the issues in more detail if anyone is interested.