I just posted an article on undistinguished identity and reputation at Between the Lines. People typically don't want their online activities correlated, but reputation is largely built from such correlations. Understanding and coming to terms with the tension between those two facts is going to be a large part of building reputation systems that work. The principles of reputation that Kevin Tew, Devlin Daley, and I discuss in our paper describing our reputation framework are aimed at lessening that tension.