The proliferation of dSLRs in society is completely mirrored here on POTN as witnessed by the pace of posting. There is so much stuff being posted so quickly that often times, a new thread can get shoved lower almost in a blink.
One thing I'm seeing more and more though: Images are being posted with a disclaimer that runs along the lines of "Straight out of the camera, didn't have time (or couldn't be bothered to take the time) to process this." Well if the images aren't compelling enough for you to take the time to make them the best they can be, why should I take the time to comment on them when they're obviously half baked?
If people truly want "hard core" C&C, there is a section for that and it also never hurts to flat out ask for it either. By and large, relative experience level shouldn't matter. If you like something, say so. But, put some meat on your comment. Don't just yack up "Nice Shot" and move on. Even if you have no clue as to the technical requirements that made the shot work, there was obviously an aesthetic quality to it that hooked you so say something about that!
Jeff25rs above me makes a good point regarding how repetitive critiques can become. So many people who are new to photography and/or new to POTN could learn a lot by just taking a stroll through the different sections before they post an image or start a thread. If they'd apply just some of what they discover by doing some reading, there would probably be a lot less of the same basic errors over and over again. And by basic errors, I mean crooked horizons, dust spots, cropping out bits and bobs around the edges of the frame, simple composition adjustments via crop, etc. Stuff that can be seen and understood without any graduate-level help.
So that's my $0.02 worth...