Interesting examples, terrible argument! No substantiated claims whatsoever! Shirky obviously thinks he is pretty smart and does not have to produce any real arguments based on evidence.
"They are built to be human-usable (...) are targeted primarily for storage/retrieval of personal information and serendipitous discovery of group information . (...) The development communities for each are abuzz with ideas for exploiting the structure"
S. Bindelli, C. Criscione, C. Curino, M. Drago, D. Eynard, and G. Orsi. OTM '08: Proceedings of the OTM Confederated International Workshops and Posters on On the Move to Meaningful Internet Systems, page 76--85. Berlin, Heidelberg, Springer-Verlag, (2008)
S. Braun, and A. Schmidt. 8th International Conference on the Design of Cooperative Systems (COOP '08), Carry-le-Rouet, France, May 20-23, 2008, (2008)
S. Braun, A. Schmidt, A. Walter, G. Nagypal, and V. Zacharias. Proceedings of the Workshop on Social and Collaborative Construction of Structured Knowledge at the 16th International World Wide Web Conference (WWW 07), Banff, Canada, volume 273 of CEUR-WS, (2007)
S. Braun, A. Schmidt, A. Walter, and V. Zacharias. Good Tags and Bad Tags - Social Tagging in der Wissensorganisation, volume 47 of Medien in der Wissenschaft, Waxmann, (2008)
S. Braun, A. Schmidt, and V. Zacharias. Workshop on Productive Knowledge Work : Management and Technological Challenges (ProKW), 4th Conference on Professional Knowledge Management - Experiences and Visions (WM 2007), (28-30 03 2007)
S. Braun, A. Schmitz, and A. Walter. Proc. WWW 2007 Workshop on Social and Collaborative
Construction of Structured Knowledge, Banff, Canada, (May 2007)