Ward described his wiki conversation with Thompson as an especially informative experience. I have constructed an experiment using the Activity Plugin and the Roster Plugin to capture an index into their collaboration.
Ward & Thompson Collaboration code.fed.wiki wellspring.fed.wiki
ROSTER Ward & Thompson Collaboration TWINS 2 CONVERSATION
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The Activity Plugin makes Recent Changes work. The example customizes the activity item to show a specific subset of their conversation: only the pages they have forked from each other.