The broader picture on paid downloads has been disappointing, though a sluggish plateau appears to be ending.   During its most recent quarterly review, Apple chief financial officer Peter Oppenheimer revealed cumulative song downloads of 8 billion, since a mid-2003 start.  "The iPhone OS 3.0 software allows customers to wirelessly download movies, TV, and audio programs directly to an iPhone or iPod touch and I am pleased to report that as of last week, customers had purchased and downloaded over 8 billion songs from the iTunes Store, yet another remarkable milestone," Oppenheimer stated. 

Oppenheimer squarely pointed to wireless, direct-to-device downloading capabilities as the catalyst, a nice outgrowth of iPhone and iPod touch success.  The iTunes Store remains a totally dominant provider of paid downloads. 

As for plateaus?  Starting in early 2007, the iTunes Store established a yearly sales pace of about two billion annually.  But things change: in January of this year, Apple revealed a cumulative total of 6 billion, pegging a year-end estimate of at least 10 billion - more than double the previous pace. 

Apple 3Q09 Filing