I think one of the most groundbreaking ideas they have is "flipping the classroom" [1], where students watch Sal's videos at home before class for homework, then in class they work on problems with the teacher and other students. That's where the ability for teachers to track and target deficiencies really becomes powerful.
I have seen this firsthand in Massachusetts and it was very powerful. The kids were all clustered around iPads or Macbooks, helping each other, doing problems, and reviewing what they learned for homework. The teacher was rotating around the room, helping stuck kids, encouraging others to do peer-to-peer coaching, etc. It was so absurdly different than how I "did school," yet so logical. The teacher felt she could now really differentiate her instruction, and the kids were impressively engaged. Gone are the days of 40 minute lectures and 10 minutes of practice— you know, where the kids who got the lecture blaze through worksheets and the rest sit dumbfounded and then take all their problems & questions home for the evening.
All that to say: yes, a dude sketching some problems on a tablet is not the "revolutionary" part (if there is one at all) of Khan Academy.
[1]: http://www.usatoday.com/life/people/story/2012-05-30/sal-kha...