Journal: Digital Camera locator

I recently bought a new digital camera, and I noticed that it automatically adds meta-data about the time, camera type and settings to each of the jpeg images. This got me thinking about cool things to include in the metadata .... Has anyone tried adding a GPS reciever to a digital camera, and recording the GPS coordinates when each picture is taken. The coordinates could be extracetd from the images later, and used index a database of images by location. Second, does anyone know if the format for the embedding the camera meta-data in the images is public ? I'd like to write a toolkit for extracting the data from the images.