While iTunes’ App Store is certainly a groundbreaking initiative that has changed the mobile content landscape, music still rules in the iTunes world.

According to a new report from NPD Group, 82% of iPhone and iPod Touch users have bought music from iTunes and 56% say they purchase music there exclusively. While the report says that “virtually all” iPhone and iPod Touch users have downloaded a free app at one point or another, it offers no data on what percentage have paid for an app compared to paying for music, a data point that would help bolster its conclusions.

From the release: “Sales growth in digital music has been slowing, and some of that decline might be related to the distraction from apps; however, iTunes shoppers are still completely engaged with music, whether it’s about listening, discovering or buying,” said Russ Crupnick, vice president and senior entertainment analyst for The NPD Group. “Apps and video certainly do compete for consumer dollars, but they can also be used to promote music and re-energize digital music and video download sales.”

Also from the report:
- Two out of three iPhone and iPod Touch owners who have downloaded apps say they use them regularly, as opposed to briefly.
- Nine out of 10 have downloaded a free app, which NPD says could lead to upselling users from free to paid versions of the same app.
- 69% of iPhone and iPod Touch owners who have not yet paid for an app told NPD they are interested in possibly doing so in the future.

Music apps and their place in both the mobile and music industries will be the central focus of Billboard’s Mobile Entertainment Live: The Music App Summit, taking place Oct. 5 in San Francisco. Keynote speakers include Dave Stewart, Janus Friis or Rdio, Christy Wyatt of Motorola, Evan Harrison of Clear Channel, Matt Murphy of Kliener Perkins, Ge Wang of Smule, Jim Lucchese of The Echo Nest. The conference includes the Music App Awards, which will recognize the best apps of the last year. Visit MobileEntertainmentLiveFall.com for details on the program and to register.