It's like teaching a programming class in D--yeah, the language is nice, but it's not what people use.
This is a lousy example that works against you. As many programmers have, I learned one programming language (Java) at Uni and have *never* used it since. I have since, however, worked in asp, c, c++, c#, asp.net, perl, sh, vb, vbscript, ruby, python... and probably more that I can't remember; none of these ever presented any problems to me, nor should they to any real programmer, regardless of previous experience.
The point, as many other people have been saying, is that if the principles are taught well, rather than procedure, then the platform becomes absolutely irrelevant.