Think sport; think coed. What do you think of? Maybe it's just me, but I think of mixed gender athletic activities.
Because surely people don't mean to use coed as a noun referring to the antiquated (well not that old but still...) use of the term that describes female college students.
But, yes, that still happens. The Title IX blog recently noted that in a suit being brought by a young woman's parents against her school the female student was referred to as a coed. First of all, you can check out their link to a post about the egregiousness of the term and its origins in the belief that women as students were add-ons.
Second, the young woman who is experiencing discrimination in the school's apportioning of athletic resources, isn't even a college student. This, to me, illustrates the interesting mental intersections of women's sports and general sexism. Women's sports, like female students--once upon a time--are add-ons in many people's minds.
Even Birch Bayh, who introduced Title IX in the Senate in the early 70s referred to female students as coeds in a speech he gave against the weakening of the legislation. I am sure he wouldn't do that today, but it serves as an example of just how ingrained sexism is and how it manifests itself in our speech.