Blueline Academy on Justin.tv continues now into its third month. In the past 90 days, this format has demonstrated itself to be an excellent means of interesting folks in classes and further work with the material.
Something that I had not anticipated at first, which has proven to be a major hit with class members, is the review of homework from other participants. Although justin.tv does not have a co-hosting feature (yet) it is simple enough to have folks email me their gaming orbs before class so that I may review and comment on them during the broadcast.
The chat provides a convenient venue for asking questions during the class. And since the chat is literally off to the side, I can address questions immediately or hold them in abeyance until a suitable point in the class -- whichever suits the moment.
This definitely improves the online classroom tutorial interaction.
By the way, justin.tv is just one of several such hosting situations. And, it may not be the best. It just happens to be the one that I am experimenting with at the moment.