A Guardian article from  Jess Zimmerman. The arguments are inelligent and Zimmerman recognizes the value as well as the dangers of socially-enabled biofeedback devices. The kGoal (tagline 'Fitbit for your vagina') actually sounds like rather a good idea, but the cons are significant. I particularly like "But the pitfall of data devices ... is that they hijack your reward pathways" and "The quantified self ... takes theaggregate self out of the equation". Good food for thought, and some important lessons for those seeking to gamify many things, including learning and teaching.