Whenever new technology reportedly meets the iTunes store, it's prudent to check Apple's online storebag protocol to see what's what. Today, I downloaded the latest storeBag.xml from Apple's public iTunes server. What I found was this:
There appears to be a new service, labeled "p2-panda" that offers access to the same functionality that Cory reported on last night. Specifically, the panda calls include StoreFront listings, Genres, Top Fifty listings, and Updates. If nothing else, this independently confirms functionality seen from those screen shots.
At this time none of the calls appeared to function--whether from a Mac or from an iPhone--but I do not have access to the AppStore software itself, only to the protocols and web browsers. I'll try testing periodically in case the services pop back online.
Update: p2 likely refers to Purple 2, the iPhone code name. (Thanks Ryan)
Update 2: iPhone developer asap18 reports that the AppStore allows users to search for iTunes music as well as applications. This leads him to believe that AppStore extends the core iTMS functionality on the iPhone.