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].
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.