Warner Brothers handles distro for some Viz stuff and now I guess Sentai's stuff. Most of Sentai's stuff usually goes up on the Anime Network, never heard about it being on iTunes though.
http://www.animenewsnetwork.com/interest/2011-01-09/signed-k-on-guitar-gets-9999999999-yen-bid
^ crazy.
I only just found out yesterday, I went of iTunes to check the free tvshows, and the first episode was there so I got it.
I want a K-On guitar.....