What language would you use to teach a beginner to program? (jclinton.posterous.com)

Depends on the time and depth you have/want.

Lua inside some game. Or assembly on metal.

I'd be interested to see the results of giving students something like "Learn Python the hard way" in a classroom situation. The tutor would try to avoid giving answers, but would guide students in discussions into getting the answers for themselves; maybe eventually showing them how to search and find answers.

As gcb says, advanced learners will benefit from building a computer and using assembly language. But this is not something you could do with general students.