Feeds are also known as RSS. It was once a extra feature. But now its integral part of content sharing between sites. With improvements to Google Reader interface, its getting easier to read at one place rather scattering around with multiple tabs in browser. Further you can share the favored links as rss feeds. So integrating this content in your blog, or sharing with other friends is easier.
All this seems as a step towards semantic web.
While mentioning about feeds, full story feeds is what I prefer, as I don't have to come out of my feed reader to get the full information. Having just the topic in the feed is not worth the feed subscription. As Scoble said FaceBook is becoming an huge aggregator, Google is also catching up will lot of feed integration between their apps. Their own social network site (Orkut) is also catching up with feeds, and other face book like changes. Yahoo has a service named pipes, which helps to create custom feeds out of web-pages.
as the number of feeds grow, one thing I noticed id REST-Style urls are being used commonly. This might be because, rest-style url supports natural customization to feeds by adding words to the url which is intuitive rather a complex url,
somesite.com/feed/all
somesite.com/feed/history
somesite.com/feed/today
somsite.com/feed/userName/tag
All of them use this kinda of url rather complex query parameter style. Check google picasweb feed , del.icio.us feeds, etc
Though REST style in architecture is not widely adopted, rest-style URL is widely accepted by all and solving part of the problem in web.
