Subscribing to Content with Web Slices: I have to give Microsoft credit here — this is a pretty good idea. I could see this getting copied by the other browsers.
A Web Slice uses simple HTML markup to represent a clipping of a Web page. When a user subscribes to a Web Slice, a portion of the Web page is added to the Favorites bar.
The Web Slice or the user can specify how frequently Internet Explorer will check for updates from the Web server. The smallest update interval is 15 minutes.
To detect a Web Slice on a Web page, Internet Explorer scans for elements that are of class hslice, have an id property, and contain at least one child element with an entry-title class name.
And they kept it standards-compliant. Previously, they would have had everyone use some custom markup.