Dies und Das

Cattuto, Loreto & Pietronero managed to publish a paper about tagging titled "Collaborative Tagging and Semiotic Dynamics" in the Scientific American

Collaborative tagging has been quickly gaining ground because of its ability to recruit the activity
of web users into effectively organizing and sharing vast amounts of information. Here we collect
data from a popular system and investigate the statistical properties of tag co-occurrence.

See here (metainfo only)