Bryan Starbuck from the Windows Live development team blogged about the RSS feed support in Mail Desktop Beta.
Their feed reading features are built on top of the Windows RSS Platform. That means you can read feeds in an email application that stays in sync with feeds you read in IE7.
Go check it out: http://spaces.msn.com/morethanmail/
Note (added 5/8/06): From the comments below, we get a lot of people sending feedback on Windows Live Mail (the new Hotmail) and Windows Live Mail Desktop (the new desktop client). We can't answer those questions.
You can send comments on Windows Live Mail team (formerly Hotmail) at http://spaces.msn.com/mailcall/.You can send comments to the Windows Live Mail Desktop team at: http://spaces.msn.com/morethanmail/ Both teams would love to hear your feedback directly :)