At Gnomdex 5.0, and again here at PDC, Microsoft showed off some extensions to the RSS namespace to handle other types of data than reverse chronological order posts. LIsts and Calendar items were the two examples given.
Here, we see how IE7 generates a page for an RSS feed with extended calendar item information in it. You can see the ability to wordwheel search, sort by Speaker, Date, or Title, and filter by session type. This page was dynamically generated based on the contents of the feed. Pretty impressive stuff, with far reaching implications.