A new analysis of Apple’s iTunes and iTunes-related businesses (music sales, video sales and streaming, e-books and most importantly apps) by Asymco’s Horace Dediu has revealed that it is, on its own, one of the world’s most valuable businesses — and would be ranked at 130 on the Fortune 500 if taken separately from the rest of Apple. In addition, Dediu says that iTunes’ revenue is about half that of Google’s search business, and growing slightly faster….