This is nothing new. It is the same old phone-sex people, young and old, have been engaging in almost since the invention of the telephone. But now you can send pictures of the action. In fact a recent study shows that one in five kids have used their phones to send sexy or nude pictures of themselves.
This new twist can have consequences including charges of distributing child pornography as in the recent case of a 15-year-old girl in Ohio
There have been cases of this here on LJ as well. Teen girls can get a friend list of hundreds before the journal is discovered and deleted. But aside from such short term consequences, those pictures will outlast the Internet.
I don't think the Internet itself is causing this behavior. There is, of course, the element of peer validation as I have mentioned before. But for the most part it just seems that the Internet has made private lives a LOT more public. Another recent study shows more than half of teens reveal risky behavior online