None of the books you get from this site have DRM on them.

As of Tuesday morning, songs from Sony, Universal and Warner were found still to have DRM protection.

Macrumors claimed Sony artist Edgar Winters had DRM-free tracks in iTunes, but thetracks appear to be from other labels.

MP3, which is still the defacto standard everywhere, never had DRM so this is more about Apple and Amazon finally owning up to reality.