This is fine for an app or content that is behind a "registerwall", because you must convince the user that registering is worthwhile. But in the Khan Academy the courses a freely available. Instead of presenting me a video of Sal chatting with Bill G on the stage of TED, I'd prefer a video that is likely to expand my understanding of the universe.
That said, the sketches/mockups that led us to the current iteration of the design also included both the idea of featured content in the main video carousel and different homepage content for users who are signed in. They didn't make the cut yet, but we haven't forgotten about them.
Ultimately, I agree that we want to make it as efficient as possible to get to the content you want quickly, and I don't think we're there yet.
BTW: Sal's TED talk was very inspiring and really demonstrated the amazing potential of his work. It's great to see all of the recognition and support he is receiving and the excellent team now in place. His talk even inspired me to start blogging about Education last month -- see the first post on Education2.org [http://www.education2.org/2011/03/welcome-to-education2-org].
It's still not quite as good as a native app, but it seems like you're getting 90% of the benefit with about 10% of the work. For a dev team strapped for resources it seems like a good option.
My one complaint is that it seems wrong to have a pseudo-hover state for the entries in the lists. I don't know what standard practice is in mobile web interfaces, but it seems strange that scrolling causes elements to look selected because you have to hit a point in order to start scrolling.
I had expected that the image of the redesign would link to the main page, but annoyingly, it does not, nor is there a link anywhere else in the article.
https://sites.google.com/a/khanacademy.org/forge/for-develop...
pretty easy to keep up with the progress by running it locally and occasionally syncing.
one note: on my nexus one, the back button in the upper left of the mobile site doesn't work. specifically, after clicking on one of the list items, sliding to the right, I can't go back by hitting the button on the upper left.
www.banyantree.com