"Social Trust-aware Recommendation System: A T-Index Approach" Workshop on Web Personalization, Reputation and Recommender Systems (WPRRS09) Held in conjunction with 2009 IEEE/ WIC/ ACM International Conference on Web Intelligence (WI 2009) and Intelligent Agent Technology, http://www.wprrs.scitech.qut.edu.au/ Università degli Studi di Milano Bicocca, Milano, Italy September 15–18, 2009