https://marco.org/2010/10/06/xkcd-online-communities-2-im-so-proud-that
I’m so proud that, after having the prior edition hanging on the wall at Tumblr for three years, Tumblr itself has become big enough to have its own island in the map (near the northwest corner of the Sea of Opinions).
I hope that Instapaper is on the map by 2013, possibly as a ferry route across the mouth of the Bay of Flame (in the Blogosphere core region).