Dave Winer explained that RSS was a "juggernaut" and that OPML is "the next web."
Dean Hachamovitch and Amar showed us IE 7 under the theme "Longhorn Loves RSS." IE7's RSS support appears to be a combination of Firefox's Live Bookmarks and Safari's feed view. It's so innovative that it even does RSS auto-discovery and "shows an RSS icon right in the chrome."
Microsoft will be extending the RSS 2.0 specification and release their extensions under a Creative Commons license. The extensions seem to be primarily in simple ordered lists (not hiearchical OPML).
The core of the platform described so far seems to be a feed store in longhorn. This persistent storage mechanism will be accessible through published APIs and most or all Longhorn applications from Microsoft will be RSS aware.
We may see some of this in pre-Longhorn XP (with IE 7?)