I think that for the average enterprise user, sticking RSS feeds into their lifeblood (read: Outlook/Email) makes the most amount of sense. Most executives / desk jockeys spend a lot of their time there, and I would suspect an equal sort of treatment is applied to their email as it is to RSS feeds.

As a point of opinion, I would posit that lack of integration into other common office applications is a barrier to entry to applications soliciting the enterprise space.