Carter Jernigan and Behram F.T. Mistree, the two young M.I.T. graduates who discovered a way to identify the sexual preferences of Facebook users by analyzing their network of friends--and, in the process, underscored just how ephemeral privacy can be on social-networking sites--have published their work in an online journal called First Monday. The research, which began as a project for a computer-science class, was the subject of a much-discussed Ideas piece, in September.