I'm a bit of a history maven, so I'm actually kind of excited at the thought of what selfie culture means for future historians. At no time in history, not since the camera was even invented, has anyone made it this possible for future generations to consult /so many/ primary sources about what today is like, the youth culture and so on. Sure, it's duck faced and ridiculous, but that's where we're currently /at/ with youth culture! And in five hundred years time, there will be thousands upon thousands of primary source photographs to back up that assertion! Imagine the future theses that will be able to be written!
On a slightly more down to earth note, I'm also kind of excited at the way selfie culture is encouraging a whole generation of traditionally self conscious people to love themselves and their appearances in a way that's quite revolutionary. Look back ten, twenty years and you just don't see the kind of "hey, look at me, I'm beautiful" culture that selfies lend themselves to. In years past we might have called this conceit, and reviled it. Let's not forget that entire industries have sprung up around making people continue to feel like their appearance is inadequate!
If I'm honest, yes, I think the pictures look stupid and I do wish that people would just smile normally. But I will never be one of the people saying "gosh, take less selfies" - because a) I love the boost in self esteem it's giving to people who traditionally were denied any sense of self esteem at all (and we wondered why they had none), and b) the historical angle.
Imagine if selfie culture had existed around the time of the Russian Revolution, and Tsar Nicholas's daughters had been willing and able to take as many selfies as they wanted. Would there have been as many imposters pretending to be Anastasia if there were hundreds of photos of the real thing to compare with, as opposed to the blurry few we have? Imagine if the Ancient Greeks, Romans, and Egyptians had been part of "selfie culture" and had had the kind of technology we have now to capture themselves. I would kill (not literally) for that kind of photographic glimpse into life so long ago, so I envy the future historians who will reap the benefit of what teens are doing today.