OpenRelief is a project to build a UAV that can use advanced image processing to quickly identify information on the ground that can help relief workers. It uses APM as the autpilot and Raspberry Pi for image processing. The plan is to be able to quickly identify smoke, roads and people from the air to "help disaster relief efforts see through fog".
You can read more about the technical details in this pdf, but there are some slides and video from that below:
(Thanks to Andrew Zoli for the tip!)