In a move that some consider the first step toward allowing advertising on other Apple content areas or even iPods, Apple's iTunes will soon be ad supported, Ad Age writes (via MediaBuyerPlanner). Apple CEO Steve Jobs supports the concept of ad-supported podcasts, providing a window of opportunity for visual ads to join existing audio ads.

Though this may excite advertisers, iTunes users could be worried. Concern for users' sensitivity to the ads may be why Apple plans to place ads only in the lower-left corner of the iTunes library, at least for now.

Meanwhile, TV networks are profiting from iTunes' ad-free model, charging viewers $1.99 per downloaded an episode. However, ABC has plans to offer free versions of the shows it offers for a fee on iTunes on the network's ad-supported site. Also, this summer, NBC will launch free original Webisodes of The Office, while AOL will offer free A&E Network programming on ad-supported sites.

"The question is whether the power of free is more compelling than portability," said Ben Bajarin, Creative Strategies analyst. "It's an interesting test for ABC and we'll be watching how it affects iTunes."