as far as I am aware FF supports the col/colgroup standard just fine, what eactly were you trying to achieve ?
just because something works in IE doesn't allways mean that it is following standards, the biggest difference between IE and all the other browsers is that it lets you get away with stuff that isn't standards compliant
most of the stuff I have read where people were having problems with FF were when trying to use align, IE supports align for COL, but it is not in the HTML spec so FF does not support it. It is a huge debate as to whch is correct, but to standards it is FF that is correct in not implementing align, and IE that is wrong.