Peter Martin points to the oktrends blog - the official blog of internet dating site OkCupid. Some fascinating data there with nifty java-based graphs. They argue that younger men should give the cougars a second look. They're almost certainly right that men taking their advice would get more dates; if men there, though, are looking for marriageable partners rather than a short fling, well...I can't help but think of various Roissy posts on the topic.
One neat graph from the post, derived from OkCupid data:
I take this as further evidence of Susan's eminent rationality: we married when we were 26. Of course, my curve's declined more quickly and hers less than the averages would suggest, but playing the averages remains safest ex ante.