The Japanese should connect these vending machines that suggest a drink based on customers' gender to the billboards with face recognition they've been installing in train stations earlier this year -- unless that's what they are already doing. From Reuters: "The machines, developed by JR East Water Business Co, a subsidiary of railway firm JR East Co, use large touch-panel screens with sensors that allow the machine to determine the characteristics of an approaching customer."
The embedded digital signage bases its drink recommendations on temperature and time in addition to the customer's gender. The machines are made by Acure that has more information about them on its site.
Here's the press release in Japanese (pdf).