Google debuted a new feature — Gmail Motion — designed to allow people to eliminate the use of keyboards and mice and instead write emails using only gestures, which Gmail would track using your computer webcam and a "spatial tracking algorithm." Command gestures were simple. To open a message, make a motion with your hands as if you're opening an envelope. To reply, point backward over your shoulder with your thumb. To reply all, point backward with both thumbs.
The home page for the new application featured videotaped commentary from experts such as Dennis Tooley, Ph.D. from the "California Center for Kinesics and Paralanguage," and Lorraine Klayman, M.Sc., an "Environmental Movement Specialist at Nevada Polytechnic College."
Google did note that safety precautions should be observed before using Gmail Motion. Users were advised to clear 4 feet of space around them and to take breaks every 30-40 minutes. link: Gmail Motion Beta