The subway in BJ has the largest network among all mainland cities, I guess. What people normall do in the subway?
From my experience in Hong Kong where subway covering much smaller area than Beijing, I usually read the news from my mobile phones via GPRS. I use CSL service now, and I could enjoy the news channle, including Reuters and Dow Jones for free. Though the content is much more limited compared to the wires terminal version, it is a good resource to spend the time and learn new things.
In Beijing, seems many people read newspaper or send messages in the subways. However, if some service providers could serve the passengers free or charged mobile content, such as e-newspaper, e-game. etc, when they get onto the train, it will attract many passengers as well as advertisers, and more efficient than sending the content to someone who are working in the office or sleeping in the home. It will also be more diversified than the TV carrying advertisements all the time on the trains.
However, the problem is the mobile network doesn't really cover the BJ subway very well. sometimes when you call, the signal suddenly disappears, friends told me. So here is the tricky, don't hang off immediately, hold on for another one to five minutes with patience and the call will go through again.(hope the other party has the patience too) . The cut off of the signal will be a bad experience for passengers, but there must be a way to solve the problem some day.
Kind of like location-based service, but should be more professional and legal.