Someone else wrote to Yahoo Answers the following:
The person who takes a photograph owns the copyright to it (with a few rare exceptions such as "work for hire") and can post it as he chooses. Unless the photograph was illegally taken - which means taken without the subjects consent in a place where the subject enjoyed a "reasonable expectation of privacy" then the subject has no say in how the photographer uses it.
Examples...
1) You are on the street when the picture is taken. You have no "reasonable expectation of privacy", and you have no control at all over the use of the photo.
2) You are at a private party, drunk, as is the photographer. He takes a picture of you doing something embarrassing in front of a bunch of your friends. You have no "reasonable expectation of privacy", and you have no control at all over the use of the photo.
3) You are having sex with a boyfriend, and he grabs his cellphone to take a picture of you 'in action'. You smile and give the camera a 'thumbs up' for the picture. You had a "reasonable expectation of privacy", but you consented to the photo, and you have no control at all over the use of the photo.
4) You are having sex with a boyfriend, and he grabs his cellphone to take a picture of you 'in action' while you are blindfolded, and don't know. You had a "reasonable expectation of privacy", and you did not consent to the photo, so he may not publish it without your consent.
Note that as a separate issue, if the photographer "commercially exploits your image" then you are entitled to be paid for it - but you cannot prevent the use. {and I say, this is why a professional signs a release, as they are releasing the rights to the venue to make money from the image of you and you are signing off any monetary claim to any extension of financial benefit beyond your "model fee"}