The New York Times writes:
In advertising terms…the mobile phone remains very much the third screen, behind television and the computer. Mobile advertising has grown rapidly in markets like Japan, but outside Asia, activity is still dominated by “text and response”� campaigns that for example, ask users to send text messages for more information on a product, or enter a contest.
…
The study also showed how effective mobile advertising could be if the personal space could be entered deftly. Sizable percentages of respondents said they had visited a Web site or requested more information about a product after seeing a mobile ad.
