Identification is the psychological process that explains why magazines targeted at women are mainly full of women pictures and not of men. Leading to the strange phenomenon that the figure of women (in the western world) seem the almost only icon of desire.
Seeing the way men magazine are formatted one would expect it to be the same for women magazine but in reverse, that is, full of half naked men. But this is not the case.
Upon seeing the photo of a half naked beautiful woman a typical man would experience desire, a woman would not, she would identify with the model, she would see herself as this slim, attractive woman depicted on the glossy paper.
Furthermore it appears that the desire in women is not aroused in the same graphical way as in men.
Men are less keen to identify themselves, for instance a (straight) man would never express a compliment on another man's physical appearance but a woman would have no problem to say that such or such woman is beautiful. It can be derived from the above that some advertisings depicting handsome men are not targeted to women only but also to gay men.
Note that this is a european-based vision of the phenomenon. I haven't been able to ask the view of lesbians or gay men but if you have any documented opinion on the subject you are welcome to complete the picture.