Turning it around
So, it sounds to me like we've pretty much discussed this side of the issue to death, but David's post got me thinking about the flip side of the coin. It must happen with some regularly that teachers get crushes on their students. I've got to say that this seems like a harder place to be. As the student, you've got much more limited responsibility. You want to make sure you aren't unduly disrupting the class, and there may be a lot of wisdom in waiting, but, ultimately, it is the sensei's job to deal with the feelings that come up in his students one way or another. On the other hand, a sensei who is finding him or herself strongly attracted to a student has a lot more responsibility (it seems to me) not to disrupt or derail the students training. It seems like it would be a confusing place to find yourself.
Of course, everyone who said that such feelings don't belong in the dojo will say that again. Probably, they will think that that's true even more pointedly in this case. However, what I'm most interested in is teachers who have had experiences with this(or students who watched it happen to their teachers), how they've dealth with it, how succesful that was, and, most especially, what they learned.