This is my tiny piece of anecdotal evidence:
I'm in the South Eastern United States... and I see iPhones EVERYWHERE.
I was recently at a dance competition with folks from NC, SC, GA and more. It was all iPhones... all the time. Parents, high school kids... nearly every phone in sight was an iPhone.
Lots of dance team directors are now using their iPhones to play their music at these dance competitions... thanks to the plethora of adjustable-tempo music...