I can't believe the obvious question wasn't asked....
Will the new Windows Mail also be an RSS reader? Given that there are so many potentially similar UI elements whether reading email, Usenet News, or RSS feeds, it seems like an obvious thing to do.
Also I think you need to be prepared to take some heat for the "special" functionality that will only available on Microsoft newgroups (the ability to rate responses, show special icons etc.) There are a LOT of people that are going to say "there they go again"
with yet another "proprietary" feature.