This reminded me that I had spent an interesting while (well, an hour or so) looking at the iTunes ministore over Christmas. I am sure that this is familiar to lots of folks. It comes up as a pane in your iTunes interface. When you select one of the songs in your 'local collection' it brings up other work by the artist and shows music that folks who bought that artist have also bought.
There are times when it does not give you results at the artist level, but falls back to the genre. I was occasionally surprised when this happened. Maybe not unsurprising for,say, Energy Orchard, but you would expect early Van Morrison - St Dominic's Preview [wikipedia], for example - to be matched.
On first look, the results were sometimes potentially interesting, sometimes unsurprising.
The tight integration between computer, network and device applications is a feature of the iTunes experience. Nevertheless, I was struck by the way in which my local collection was being used to generate responses from the network service.
It is another small example of how much of what we do increasingly participates in network interaction.
Incidentally, the Top Tech Trends talks are well worth a listen. Although, it would be nice to be able to speed them up ;-)