MySpace users who reveal information about themselves will have that detail used to target specific ads at them. 

Details the users post on their profiles will now be harvested and used in conjunction with the basic information they submit in the registration forms.
Information can even be extracted from blog entries if users write about likes and dislikes and used to "classify" them to receive certain ads.
So far there hasn't been any outcry from users, but it could still be forthcoming once they realise their privacy has been compromised.