i think scheme is still great if you already know some programming because you can appreciate it even more.
My understanding was that MIT switched to python because in later courses they could actually use it to get things done (robotics, image proc, etc). While if they taught scheme they had to at the end of the course pretty much say: well that was fun, now we have to teach you something useful to get the rest of the course done.
mit and berkeley had/have the exact same "problem" with scheme (ie they don't/can't use it in any other class except the intro-to-into-cs class). This usually resulted in upped div classes spending a a class or two (basically a week of instruction, or a week of lab) on teaching the basics of the language the course is in. Though when i took the compilers course a few semesters later, the second slide of the entire course was "RTFM", and the professor dryly noted that we would be compiling a subset of python down to x86 assembler using c++, and despite the fact that he didn't expect any of us to know those languages at all, we didn't have the time to spend a lecture or discussion/lab on learning them, so we would have to learn them, on our own time.
I suppose that switching to a language that can be used in many classes is nice, but i don't think the students should have that much trouble switching if the professors supply supplementary material and they (students) understand the intro courses well enough. Plus, I think it's a good idea to get exposed to as many languages as possible, so you learn to think in a way that you can code well in any language.