How does our role as teacher change?

Thanks to Ali Hall who had noted this video by John Travers about the notation of students work using a bookmarking service such as Diigo.I love Diigo as it combines the best of many other tools on one site but I am not so sure about the kind of use John is describing is one I would rush into with high school students, probably more with tertiary ones. To me the business of commenting on blogs is still hard- I am forever wishing I was better at commenting and being able to write reflective and useful points, but my brain struggles to think of anything apart from the mundane in response to blogs and I feel I let the kids down in this area. This video seems however to make the commenting process even more separated from the personal relationship which the classroom provides. Blogging is a step away from the personal, but also opens up the process to peers in the class and others outside. This idea as shown in the video to me seems something maybe appropriate for senior classes or tertiary work. What do you think?