According to AdAge, Apple may be planning a start to advertising inside of iTunes, and potentially your iPod, very soon. From what we can gather from the article, ads will appear in the botom left hand corner of iTunes only while you listen to podcasts. If you have a few minutes...check out the whole article, its pretty interesting.
NEW YORK (AdAge.com) -- Coming soon to iTunes: ads. Apple -- a brand that prides itself on the purity of the user experience -- will soon put up billboards on its popular iTunes service, according to content partners who have been briefed on the plan. The introduction of visual ads could be the first step to allowing ads in other content areas or on iPods.