What is trickier, however, is trying to decipher exactly which movies are available for what type of purchase. Looking at the list of available titles, I could not find any clear pattern that explained why certain films are available only to buy or only to rent. I'm sure that this was all decided by the studios, based on their own internal sales trends and valuations. For instance, the majority of the "new releases," that is, the $3.99 rentals, are only available to rent. Meaning you can't buy a download of "The Simpsons Movie" or "300." This makes sense, as I'm sure the studios (Fox and Warner Bros., respectively) would prefer customers buy those films on DVD rather than an iTunes download. This is not universal, however, as some of Disney's new releases, like "Ratatouille" and "Pirates of the Carribean 3" are available for both download and rental. It should be noted these films were available for purchase before Tuesday's announcement.

Speaking of new releases, it is important to keep in mind the caveat that was mentioned during the keynote - right now studios will wait 30 days after a film comes out on DVD before making it available on iTunes rentals.