Nintendo DS has utilized this technology device-to-device without an access point (router)
http://en.wikipedia.org/wiki/Wi-Fi#Direct_computer-to-computer_communications
http://mashable.com/2010/10/25/wi-fi-direct-launch/
Communication between Wi-Fi devices isn’t specifically new. The Nintendo DS, for instance, has had device-to-device Wi-Fi interaction for some time, but the technology is proprietary.
EDIT: Beaten...







