Tabarrok mentions the issue of teaching inequality -- with the range from average adjuncts to superstar lecturers. There is no getting out of this. In fact, it is a natural result of distribution of talents (of teachers as well as students). I think free-lance professors would actually help in this filtering process, as the students would decide who the superstars are, rather than universities pre-selecting possible superstars.
To cite Metafilter (cited by Tabarrok):
Stanford’s ‘Introduction to Artificial Intelligence’ course will be offered free to anyone online this fall. The course will be taught by SebastianThrun (Stanford) and PeterNorvig (Google, Director of Research), who expect to deal with the historically large course size using tools like Google Moderator.
There will two 75 min lectures per week, weekly graded homework assignments and quizzes, and the course is expected to require roughly 10 hours per week. Over 10,000 students have already signed up.
Either way you look at it, 10,000 students is amazing. The revolution is afoot.