JK! I use cursing in my YA books. Not for sensationalism or to shock, but have you HEARD the ways these kids talk nowadays? I don't think it'd be honest to NOT have them curse (unless, or course, you're writing for MG or younger). I may be off here (I hear that a LOT), but I also think if the YA audience sees the kids speaking like they do, it may lend the author a little more "street cred."
And I'd say most of the YA books I've read have cursing (excluding the Hunger Games series, but it made up for it in uber-violence).
Now. Having said that, I still refrain from dropping any "f-bombs." No real reason. Just a personal decision.
And the follow-up to my first book has my protagonist (Tex, the witch boy) forced into joining a ludicrous suburban "gang." It's actually based on a true event that happened at my old high school a couple years ago. I mean, come on! These are spoiled, privileged, suburban kids acting like they're "living on the hard streets" and they're shooting other suburban gangsta's!
On another note, how's Mel and Stiger and anyone else doing on the East coast?