There's sexism left, right and centre. There's also racism and everything else offensive left, right and centre. I think a lot of the time they do it in a way that's parodying real-life sexism though.. Which I don't know if it's better or worse.
@protoman: As for whether you've been offended or not.. Thats irrelevant, assuming you're a man (judging from the username). If a significant amount of women are offended by it, it means it's offensive. It's not up to some male to tell them that it's not offensive.
Some people will use the argument that the people who are offended should just not play the game, but that's also irrelevant. Because there are millions of players out there, who haven't put any kind of deep thought into the subject, who will see offensive behaviour and think it's acceptable. And they will go on to affect the people who don't play the game.
All of that can be applied to any of the offensive material though. Replace women/sexism with black people/racism, etc. Is GTA offensive? Hell yeah, that's the majority of their humour. Am I personally offended? Hell no. But as a white male I have no right to tell other people what to be offended by.