I was talking with a friend of mine today who is a senior at a technology-centered high school in California. Dylan Field and his friends are by no means representative of US teens but I always love his perspective on tech practices... As someone who has argued about the challenge of Twitter being public (to all who hold power over teens), What Dylan is pointing out is that the issue is that Facebook is public (to everyone who matters) and Twitter can be private because of the combination of tools AND the fact that it's not broadly popular. My guess is that if Twitter does take off among teens and Dylan's friends feel pressured to let peers and parents and everyone else follow them, the same problem will arise and Twitter will become public in the same sense as Facebook. This of course raises a critical question: will teens continue to be passionate about systems that become "public" (to all that matter) simply because there's social pressure to connect to "everyone"?