S. Garcia Esparza, M. O'Mahony, and B. Smyth. RecSys'10 : proceedings of the 4th ACM Conference on Recommender Systems, Barcelona, Spain, September 26-30, 2010, (2010)
B. O’Donovan. (2005)introduces the notion of trust in collaborative filtering.
A simple memory based method is used to incorporate trust into a simple similarity based collaborative filtering algorithm. Results on MovieLens seem to be better than standard methods..