So do we really need new technologies like GNU Social/Twister to accomplish this, or can we just repackage the above tools to look like facebook/twitter/g+/ello, and have decentralized social platforms. The biggest hurdle I can imagine is non technical users not knowing what in the hell to do with an XML page when trying to follow a person, so I'd propose that a new link type similar to <a href=emailto:address> be established -- perhaps something like <a href=follow:myfeed.xml> -- which would open the feed in the follower's default RSS reader. And I could sort my feed into circles/groups, which are really just folders in a feed. I think this could be prettied up to look the same as and be just about as easy as twitter, with no new technologies needed. A service could host each of these components, and thus look just like a full social network as we've come to know them.
The fact that it's so often referred to as "microblogging" makes me wonder why this sort of set up isn't discussed more often (unless I'm missing it). It would also then be trivial to host your own, because really all you'd be doing is hosting a blog, and using an RSS reader. It seems so obvious to me that I feel like I might be overlooking something.