Hollywood’s leading ladies have long lent — make that sold — their famous faces to ad campaigns, but leading men are just jumping on the billboard bandwagon. Chris Noth posed for Lane Bryant, Jeremy Irons and Gary Oldman cuddle Milla Jovovich for Donna Karan, Matt Dillon and Rob Lowe both sport Skechers, and Moby and Chris Klein wear Calvin Klein. Why are ad campaigns suddenly raining men? ”The right male star speaks to both men and women,” says Harman Consumer Group’s Gina Harman, who’s paired musician Carlos Santana and ”Pearl Harbor” producer Jerry Bruckheimer with JBL stereo equipment. ”Jeremy Irons isn’t going to convince my husband to buy a Donna Karan suit, but the ad campaign’s [celebrity factor] registers with me, because I’ll wonder why he’s in it,” she says. Well, isn’t that what it’s all about?