Personally, I think not. Usually the case goes that the couple breaks up and the guy (jilted or harassed by his ex) puts them up all over facebook, all over the net, wherever, and causes a whole lot of trouble. But in my experience with people in general, it may not just be that. You never know who's looking through his phone, who's e-mailing those pictures to themselves so they can whack off, or so they can do some damage because they want to take your man. And that's under normal circumstances--imagine if the guy is off to college or in the Military, sharing a dorm with 90 other guys, half of which are gonna be asking to use his phone. That's what I think.
But am I being paranoid? A stick in the mud? He asked me to send him some and I said no, not just because of this, but because of my principles as a lady. "A picture's worth a thousand words; but mirrors keep secrets," is a saying I made up. He never pressures me about it. But what do you think? Is it ever wise to send naked pics to your boyfriend, via cell phone, email, or polaroid?