Since Seb ha cited my paper as epinions empirical analysis paper, I’d like to mention other 2 papers that analyze epinions web of trust:
the already commented Trust Management for the Semantic Web and the new Propagation of Trust and Distrust.
As a side point, note that we collected datasets of different dimensions. I collected only 49.290 Epinions users because I was following only “this user trusts X” links. Richardons et al. collected 75.000 users (but used only 5.000 of them); I think they followed also “this user is trusted by” links. Guha et al. had access to the real dataset of Epinions which consists of 130.000 users. Note also that Guha et al. had access also to the web of distrust (a sort of black list) while this information is not available on Epinions.com and hence not downloadable.
This post also appears on channel social software