This is just awesome! I think that is kinda the same community effect you see on StackOverflow but applied to a class. You’re building, literally, a *virtual* open classroom. Which should be great to both your students and other students all over the net.
Two ideas came to mind while reading your post (and the twitter feed) maybe use Cloud9 for development so everyone has the same environment. And how about something like CodeEval but maybe resetting it every semester or just not displaying others’ answers until after the due date of the Task/Challenge. #ThinkingOutloud