Very interesting: on the podcasters mailing list, Russell Holliman discovered that iTunes will download video enclosures as well as audio enclosures, and because iTunes can render Quicktime movies, it’ll play them too.
Neat. I think demand for displaying show notes will grow pretty quickly — which Apple could easily do — which would make iTunes a killer aggregator for the mass market. (If you think about it, this wouldn’t be that hard… and then one would have to ask: why confine it to enclosure-enabled feeds? Why not any feed?)