For aerial video the Hero 3 is a good starting point. The video quality is ok especially for just playing around. The Hero 3 is not a good choice for aerial photos. I don't have a way to switch the camera from taking video to taking stills. With the Sony NEX 5N I can switch between photos and video from the ground with the flip of a switch on my transmitter, through an LED remote sitting in front of the camera. With the Hero I can grab stills from the video, but I can get a much higher quality photos from the APS C sensor in the Sony in both still and video modes. There is also a lot of fisheye with the hero that becomes distracting.
I believe putting a good quality camera in the air has some interesting possibilities such as real estate work, I've also does a few large group photos from the air. There is some question as to how legal it currently is in the US, but Obama has given a directive to the FAA to formally allow drones for commercial use in the USA by 2015. Currently most other countries around the world allow for drone use on commercial work. Many of the tv and movie shots are now being done using these types of small RC helicopters.
Here is a photo of helicopter I am using now...