In spite of the fact that the iphone/ipod touch has a high internet browsing rate, it would seem that it is the Symbian mobiles which include many Nokias, that get the highest click-thru rate on adverts. Mobile ad optimiser, Smaato looked at the average click thru rate of over 3 billion served ads. Using that as an index of 100, they found that Symbian handset users rate was an impressive 169 points. iphone was the next best at 119. Blackberry, in particular, showed a low index score.
More information on Smaato’s site here.