Hackathons are like gyms
medium.com
medium.com
not to mention the great community that springs up out of it!
It's actually an extremely effective way to give new people a wide basing in computer science and, more importantly, get them excited.
I'd love to see more marketing to new people in regards to hackathons.
Why hasn't this happened yet?
Code.org so far has just been a bunch of big names putting their name on something to make noise. Very little real change from what I've seen.