Winer is right, and I'm surprised nobody is writing about this or calling much attention to it. There's enormous potential marketing value behind domains like "beatles.music" or "harrypotter.books" or "superman.movies".
With the advertising and reach of companies like Amazon and Google (or even Warner and Sony), I think these new domains have the power to split the web, and potentially turn .com, .net, and .org into something of a ghetto (sorta similar to how .biz and .name might be viewed by Joe Consumer now).
On the other hand, it may well be meaningless. I'm continually surprised to see big companies use facebook.com/[companyname] in their advertising too.