My instinct is that cheerleaders don't improve results for sports teams, but that that also isn't their function.

On the original topic, I've actually encountered the situation of "environment filled with dude programmers with poor social skills suddenly gets a few very attractive ladies who have incentives to be nice to them." My frat went co-ed senior year.

To put things mildly, productivity did not improve.

On the other hand, a lot more guys wanted to join up. So my guess is that the office cheerleaders do not make existing programmers more productive (and may in fact do the opposite), but that they may make the office more desirable as a work environment to prospective hires.