More promiscuous than when?
At the end of the day, there are more options for women available now to stop themselves becoming pregnant, sex is portrayed more in the media and the social double standard of women having to keep themselves 'pure' while blokes $hag anything that moves is being broken down (to an extent - I know there is still the stud vs. $lag double standard).
So yes, I think we are becoming more promiscuous, but I don't think it's neccessarily a bad thing.