Since I was recently appointed as maintainer for GNU Shogi, this actually interests me quite a bit. One of the ideas far down on my TODO list was to make a version of it for the iPhone and possibly other mobile phones.
One thing I find weird is this comment from the post: "a big-box retail store could reasonably claim ignorance to the contents of a prepackaged product, which Apple with its per-app-review process cannot". AFAIK, the per-app-review process does not include analysis of the source code, which I believe is not even submitted to Apple. So they can't actually check whether the app infringes on GPL software or anything of the sort. Their review is mostly targeted at functionality/usability stuff, and is made on top of the application binary itself. So putting the responsability on them as Distributors would seem mostly mistaken. I do think they are more prone to be considered a store, exactly like Best Buy in the example.