A company in the UK called Node also provides a solution for location based media. They have a number of implementation partners in Europe and the USA, and are already live at several sites. I don't know much about the GPS Ranger platform, but I do know that Node provide a complete platform including all hardware and a hosted website for creating experiences, and the platform was built from the ground up with location based media in mind, rather than attempting to modify existing technology to suit the need (not a good idea ;-) ). The battery life is 8 hours of continuous video playback, and the video and audio quality is wonderful - I saw it demo'd at an exhibition in London.