RSS 2.0 has an interesting feature called enclosures. It basically lets you have a link in your RSS feed that points to a media file or something so that you can download it in advance so it plays without having to wait for it when you get to it. It's moving blogging to be more "push" than "pull", but that's a good thing for big files. It certainly fits my blogging/browsing style and makes a lot of sense in the context of RSS.
UPDATE: ChrisDodo on #joiito just mentioned a point that I'd missed. The bandwidth issues. I guess the aggregators are going to have to be smart and allow you to filter stuff so you don't end up with tons and tons of media files hogging your bandwidth.