The Wall Street Journal takes a look at the Digital Multimedia Broadcasting (DMB) mobile television networks in Korea:

With almost an entire country able to watch video just about anywhere it wants, South Korea's experience can provide valuable lessons for companies in countries still on the threshold of the mobile-video revolution. Among those lessons: what kinds of programs bring in the most viewers, how advertising has had to adapt -- and how difficult it is to make money from the new services.

There’s a lot of statistics and usage scenarios mentioned in the article. But one of the biggest distinctions with DMB in Korea are the two kinds of services: T-DMB which is a free ad-supported terrestrial network with a variety of devices (navigation, mobile phones and MP3/personal media players) and S-DMB which is a subscription service which is mostly tied to mobile phones.

Korea Times: DMB Has More Viewers but Ratings Modest (August 3, 2008)