RSS and the dynamic WWW

In "Blogs, Wikis, Podcasts", Will Richardson gives a few examples for how to use RSS in the classroom. Clearly, if the course requires the students to post their work or writings to a blog, the instructor would benefit greatly by using an RSS aggregator to collect and easily review student work in one location. He also makes the case for students to collect information using RSS search feeds, which sounds really cool. I have heard about these, but never really understood what they were capable of. In a nutshell, you can search a news site for a keyword (say, Mars), and save that search as an RSS feed. That feed would pipe any new articles about Mars directly to the aggregator as soon as it's published. That's pretty sweet!