Blogging has always been a social online activity and Six Apart has been an early leader in blogging with MovableType. VOX, their social blogging platform enables private and social blogging blended with multimedia and integrations with a number of third-party social services. As a bibliophile, I love Vox's integration with books.
As I explore it further, I'm curious to learn how VOX extends the social aspects of blogging.
Social networking is likely to become increasingly integrated with blogging. Both SixApart and Auttomatic are headed in this direction with VOX & MovableType and WordPress & BuddyPress respectively.
MovableType has also gone open source. This competition should be good for both companies and for their customers.