I think mobile advertising is going to be huge.
It's very possible that advertising business models will simply never do as well on mobile devices as those oriented around transactions.
While Google no longer has a search engine operation inside China, it has maintained a large presence in Beijing and Shanghai focused on research and development, advertising sales, and mobile platform development.
I credit Google for having the foresight to identify threats to its main business of selling advertising against search results. The potential loss of market share in the mobile space led them to the Android acquisition.
Advertising is the art of convincing people to spend money they don't have for something they don't need.
Mobile communications and pervasive computing technologies, together with social contracts that were never possible before, are already beginning to change the way people meet, mate, work, war, buy, sell, govern and create.