Social media is an effective marketing and advertising channel, according to 329 brand executives surveyed by PulsePoint Group and the Economist Intelligence Unit for eMarketer in February of this year -- but they're not sure exactly how effective it is, as they still don't have a handle on social media metrics. The good news: large majorities of respondents agreed that social media was effective in basic and important ways. Overall 84% of respondents said that social media improved their marketing and sales effectiveness, 81% said it resulted in increased market share, 68% said it resulted in improved product or service …

Social media holds enormous potential as a teaching tool, but also some obvious pitfalls, including the possibility of inappropriate teacher-student interaction (which of course exists independently of social media). On that note, in recent years there have been several dozen incidents involving inappropriate behavior by teachers using social media in New York City alone. Now, to keep the pedagogical relationship and lines of authority clear, New York City's Department of Education has issued a set of guidelines for teachers who use social media for educational purposes.