Microsoft has a new home page for RSS in Longhorn. Here’s a reasonably simplified explanation of RSS Support in Longhorn. The specification itself is here.
This license information appears at the bottom of the specification page:
Microsoft’s copyrights in this specification are licensed under the Creative Commons Attribution-ShareAlike License (version 2.5). To view a copy of this license, please visit http://creativecommons.org/licenses/by-sa/2.5/. As to software implementations, Microsoft is not aware of any patent claims it owns or controls that would be necessarily infringed by a software implementation that conforms to the specification’s extensions. If Microsoft later becomes aware of any such necessary patent claims, Microsoft also agrees to offer a royalty-free patent license on reasonable and non-discriminatory terms and conditions to any such patent claims for the purpose of publishing and consuming the extensions set out in the specification.
Dean Hachamovich has some comments here.
Oh, and those who were wondering whether XML support in Office 12 will be a big deal can now put their skepticism to rest. Yes, this will have huge implications for Office 12, and I think you can safely assume that the ability to create and consume RSS will be a big part of the next version of Office.
Ed Bott 
This is great news, in that it simplifies file formats and sharing for users and for developers. Lots of people are already writing their “Ho-hum, hey, isn’t Apple great!” columns about Longhorn, but for those following its development and progress, the second half of this decade is going to be a blast.
Hey, have you seen http://minimsft.blogspot.com/ recently? Apparently Joe Peterson, VP in charge, has been fired because of Longhorn’s abysmal record.
Quite rightly so – they’re dropping features like crazy and the ship dates just keep slipping.
As a well connected journo do you have any inside dirt?