This post by Jan-Lukas Else resonates a lot with me as I am building the Friends Plugin with exactly the attempt of integrating the social aspect of blogging more into your own blog.
The Friends plugins joins the aspect of reading / following your friends’ blogs / twitters / etc. with seamless posting on your friends’ blogs, if you have established a friendship, thus (theoretically) allowing a full social experience (Facebook-like), just in the blogging world, not tied to a single vendor.
Having implemented this as a WordPress plugin brings the inherent requirement (with no other implementations yet, which are very much possible) of WordPress, but at the same time I think it lowers the barrier of entry, since it’s relatively easy to get a new WordPress blog hosted where you like.