As reported earlier this week at TechCrunch and podcast at Podtech.net, the latest big news from Yahoo! is that RSS is fully integrated with Yahoo! Mail and Alerts. As John Furrier noted today and Dion Hinchcliffe previously argued in RSS is the Web 2.0 "Pipe", RSS is fast becoming a central piece of the Internet's glue, plumbing and infrastructure.
One last note: this move by Yahoo! is another indication of a very savvy company. You can find a good analysis of how they're a bit underestimated in this new Wharton School piece Yahoo's Strategy: Stay Out of Microsoft's Crosshairs?.