I've always said the sex ratio is an important aspect of any dating market. Here is an article from the New York Times on the ramifications of the shift to more females in college. It is clearly a better time to be in college than when I was there. Alex Taborrak discusses it here, and here he provides a good example of how small differences with large opportunity costs can dramatically alter the "power" in a relationship.
Casual observation here on campus suggests males would be wise to lock up their significant other with a ring now, because they won't be able to do better after school is out.