Ah, there are rumors going 'round that the meatspace identity of The Blogger Known as Atrios will soon be revealed. Whether or not this is all just gibberish, I'm really surprised that he has not been "outed" before now.
From a practical standpoint it certainly must be difficult to maintain general anonymity while engaging in the sort of networking and collaboration that is commensurate with his position in the blogosphere. It seems that the mainstream media have seized upon blogging as their plaything of the moment. For better or worse, if Atrios is indeed "coming out" at the DNC, blogs and bloggers will certainly attract even more attention.
Whenever your blog is getting ~100K hits per day and you are raising big $$$ for candidates it seems that being anonymous will become more of a hindrance than benefit. I think Markos is a wonderful example of someone who is able to leverage the power of a blog community, and work to induce real change in the political system. Once Mr. Atrios climbs away from that big blue dot of anonymity, I think we will have another powerful advocate for progressive interests. We need all the help we can get.