Folksonomies provide a rich source of data to study social patterns taking place on the World Wide Web. Here we study the temporal patterns of users’ tagging activity. We show that the statistical properties of inter-arrival times between subsequent tagging events cannot be explained without taking into account correlation in users’ behaviors. This shows that social interaction in collaborative tagging communities shapes the evolution of folksonomies. A consensus formation process involving the usage of a small number of tags for a given resources is observed through a numerical and theoretical analysis of some well-known folksonomy datasets. Categories and Subject Descriptors H.3.4 [Information Systems]: Systems and Software; H.3.1 [Information Storage and Retrieval]: Content Analysis and Indexing; G.2.2 [Mathematics of Computing]: Graph Theory General Terms Human Factors, Measurement, Theory Keywords folksonomies, semiotics, semiotic dynamics, small worlds