The IAB released its half yearly digital ad revenue report for the US market earlier today. Total "online" revenues were approximately $17 billion, compared with $14.9 billion a year ago. Search was the single largest revenue category and has been for some time. It accounted for 48% of total digital ad revenue in 1H 2012 or $8.1 billion (vs. $6.8 billion in 2011).

Mobile revenue for the first half was $1.2 billion or 7% of total digital ad revenue. That compares to $636 million for the same period in 2011. Ironically the MMA is recommending that brands and marketers devote 7% of their ad budgets to mobile. 

As might be expected, the IAB said that mobile was the fastest growing of the various digital ad categories it was tracking. 

If we extrapolate from the numbers in the report we can project that full-year US mobile ad revenues will come in between $2.4 and $2.6 billion depending on how good Q4 is this year.