Yes, the more I think about it the more annoying I find it. At first I thought it was just a kind of cutesy sound bite, but it IS derogatory, quite right. At least the phrase recognizes the fact that it isn't like man-porn, but why "mommy porn"? All women are not mommies (despite what certain politicians apparently wish to happen) and we are not cutesy, to be condescended to. Grrr.