I know a lot of people are predicting larger iPad sizes in the (possibly even near) future, but Apple is attempting its second "pixel perfect" UI. As oppose to Android for instance (or Mac OS), Apple is locking itself into set resolutions (if preliminary mock-ups are believed) and, and although doubling or quadrupling pixel counts for apps could be relatively seemless, some apps, bitmap graphics and even websites creating different versions could get complicated quick. iPad versions of apps are already getting very specific about new real estate (not simply scaling). I can't imagine creating separate iPhone, iPad, iPad with slightly higher resolution, iPhone with slightly higher resolution, next iPad with even higher resolution, etc. versions of every app/mobile website.
iTunes LP is also a pixel locked format. I'm sure Apple is eyeing the future, but I'm trying to figure out how iPhones will meet or surpass the Nexus Ones resolution or the iPad will increase 2" in height, etc., thus changing ratios with such specific presentations.