Did Comcast partner with Khan Academy just to get new, low-income customers -- and then drop the ball? (Perhaps.)

[youtube=http://www.youtube.com/watch?v=zxJgPHM5NYI&w=600&h=315]

By now, you've probably heard of Khan Academy -- hell, it got a 14-minute profile on 60 Minutes a while back (embedded above). It's an online education community that strives to create a new model for how people are educated around the world. It's gotten a lot of buzz and, while it has detr…