ON THE RADIO: This week, San Francisco's local radio guru, Michael Krasny, hosted Sal Khan (you know), Sebastian Thrun (Udacity) and Anant Agarwal (MITx), with a cameo spot by Ben Nelson of the newly launched Minerva Project in a broad discussion about the role of online education. (Here's the archived hour-long chat and web comments.) Lots of questions raised about whether students lose out on the "community" aspect of online school. Thrun noted that online contributions by students can be enormously rich: he described how one "fairly mediocre" lecture he gave was turned into a "world-class piece of information" when students started posting details he had left out. "We have to rethinking what community means," he said.