The discussions going on all over the J-blogosphere are nothing short of disheartening, and to that I have little to add that hasn't been said already. One point I would like to make, however, is about the side question of whether or not this is more of a "Modern Orthodox" problem than everybody else.
Personally, I agree more with Sephardi Lady than Harry Maryles that it is not just an MO issue, but I do think that there is a large difference in the causes that bring this problem about between the communities. It's almost as if the response people had to kids who were "off-the-derech" was to take things to the other extreme... and in the wrong communities. A decade ago, and continuing on through today, we see teens in yeshivish communities who feel like they have little freedom in the community 'rebelling' and doing all kinds of things, including those detailed in the above pieces. The (IMHO correct) response was pioneered by R' Yaakov Horowitz and others to encourage parents to not pressure their children unfairly [among other ideas] to ensure their happiness and discourage their desire to do a lot of the things they were doing.
But for some reason, it seems that parents in Modern Orthodox homes have followed the same ideas... but they should not have. The teens in Modern Orthodox homes are generally not doing drugs/smoking/drinking because they are too pressured, but often because the reverse is true: The rules and standards they are (or are not) held to are simply too loose. Where does a parent get the idea that allowing their teenage son or daughter to go to Miami - unsupervised - is a 'freedom they need'?! That implies to the teen that their parents understand (at least to some extent) what is going on down there, and that they're "okay with it".
At this point, I think most of us know the dangers of parents being too harsh, too tight, too controlling, and pressuring their kids too much. But we must also be aware of the problems that exist on the other end - being too loose, too lax, allowing your kids too much 'freedom' without having to answer for what they're doing... with who, and where. Yes, balance is extremely hard and varies from child to child - but I think that it's plainly obvious to any observer that a lot of these parents don't seem to be anywhere close to achieving a proper one.
It's time to find a better balance - not getting crazily drunk on Purim is probably not a bad place to start.