Horace Dediu of asymco posted this chart (below) to his Apple trend-tracking blog this week, showing that, finally, app downloads have overtaken downloads of songs on iTunes.
A few weeks ago, at WWDC, Apple announced it reached 15 billion song downloads and last week, iTunes hit 15 billion app downloads. Because the milestones were less than a month apart, Dediu says that it's a safe assumption that, by now, apps have overtaken songs.
Dediu had originally guessed that the cross-over would take place at the 13 billion milestone at the end of 2010, but as it turns out, it took a bit longer. This was due to an unexpected jump in song downloads, app download rates that were more volatile than expected and other factors, Dediu says.
Also of interest: the 15 billion app threshold took 3 years to reach, while the 15 billion song download took 6 years, 10 months. This equates to rates of 31 million app downloads per month and 12 million song downloads per month.
Including books, but excluding video, that means the App Store now sees at least 44 million new content downloads per month.