I just set up a The Linguist podcast and published it to the iTunes music store.
iTunes RSS is funky, to say the least. Sure, it adds a whole bunch of categories, some of them of dubious value. But others have covered that exhaustively.
What bugs me is that my RSS feed was accepted just fine the first time, when I submitted my podcasts in standard WordPress RSS 2.0 format … but that when I went through the extra effort of supplying iTunes-requested RSS, the iTunes music store barfed on the feed.