• by Erik Sass  @eriksass1, May 18, 2009

As part of the promotional blitz for Glee, an offbeat new comedy series about an aspiring high-school singing troupe, Fox Broadcasting is the sole sponsor of the iPhone app for IHeartRadio.com, the national music portal created by Clear Channel Radio, which runs Monday and Tuesday of this week.

The sponsorship for the show, which premieres Tuesday after the "American Idol" finale on Fox, includes a "roadblock"-style or "gateway" ad that appears while the app is loading, and then once ever three user clicks during the visit.

Fox is the first national advertiser to buy sole sponsorship of an Iheartradio.com iPhone app, marking another step forward for the Web site, which was launched without fanfare by Clear Channel in summer 2008.

The on-demand music service draws together music and video content from over 750 Clear Channel Radio stations (200 via the iPhone app) offering users free streaming audio monetized with video, audio and display advertising. Jeff Howard, the president of Clear Channel Radio sales, said the company has also worked with Fox to do shorter on-air spots and "blinks," as well as Web site takeovers.

The pool of iPhone app users is substantial, with around 10 million iPhones sold in 2008, and another 4.4 million in the first quarter of 2009. Of these, 93% have downloaded apps, and 60% use the iPhone to surf the Web at least once a day. Moreover, iPhone owners obviously sport attractive demographic characteristics -- with 50% under the age of 30, most relatively well-educated.

In October the IHeartRadio Web site was the most popular free media application on the new iPhone, and the seventh-most-popular app overall, according to Evan Harrison, the president of Clear Channel's online division. In April, the Iheartradio.com app was the third most-popular at the Apple store. (On another mobile front, last week Clear Channel said it was the most popular app among BlackBerry users).