I am most excited about the machine learning course, since I could use the structure to go through Andrew Ng's lectures; also the ones from 2008 are already out of date.

As for the AI course, I'm skeptical, frankly. Sign-up right now has meant putting your name and email address. There is a big difference between spending 2 second to fill that in, and spending the amount of time necessary to finish the course. You come to a website that sounds like making robots and turns out the class is about developing pruning heuristics for search trees, do you stick with it? Maybe...but I'm going to save my awe for how many people complete.

I praise Stanford (CS) for thinking up this idea. Like Khan, they are going to reach a lot of people, and I think its particularly useful for motivated learners who, for whatever reason, are stuck in a place that you can't take a good AI course or can't afford one. Ultimately, though, the course is going to require drive that a lot fewer than 65,000 have.