As I said in another part of the thread, having it later in the curriculum makes sense. I'd love to subject everyone to a Programming Languages course. At Virginia Tech, they called it Comparative Languages. Here at UD, there used to be a Junior level SICP course. I wasn't around for it, but I think it was brilliant and well-timed. A lot of the problem came with trying to move those realizations earlier when folks aren't as ready for it - plus, all the other associated problems I raised.