This paper deals with how to calculate semantic similarity between user profiles. They want to find for example similar users, which share common interests.
D. Laniado, D. Eynard, and M. Colombetti. Semantic Web Application and Perspectives - Fourth Italian Semantic Web Workshop, page 192--201. (December 2007)
P. Bonatti, and F. Mogavero. POLICY '08: Proceedings of the 2008 IEEE Workshop on Policies for Distributed Systems and Networks, page 11--18. Washington, DC, USA, IEEE Computer Society, (2008)