http://www.adweek.com/aw/content_display/news/agency/e3if5f773e59310e059c43c985188622dc1
With Apple and Google in stiff competition for mobile advertising dollars, it's useful to review how much money is at stake.
eMarketer predicts that mobile advertising across all principal formats -- display, search and messaging-based -- will reach $1.56 billion by 2013.
Commensurate with its status as an emerging channel, mobile advertising will achieve a lofty compound annual growth rate (CAGR) of 37.3 percent between 2008 and 2013 -- considerably higher than online ad spending as a whole, but more in line with emerging online formats such as digital video.