phred, that isn't necessarily true in all cases. I am pretty much in the same age bracket as King (TheOriginal), as scary as that is *grin*... I didn't realize we were that close, but I am within 6 months of being 23, and I have noticed the same thing.
however, I am doing the college thing and I just find so many people here who are still being supported by there parents still act much like children. I myself still consider myself a child, but I am very independent. I pay my bills, pay for school, work for the school, etc. I have fun on occassion, but I have my priorities pretty straight, i would like to think. However, I still see many people who think their parents will support them forever.
I agree that maturity is just a state of mind and it doesn't have anything to do with age, but I think one can also consider themself a child while being mature as well. I constantly find myself surrounded by people that don't seem to be able to take care of themselves. When presented with a situation they almost immediatley tell there parents in the hopes that they will solve it for them.
Not completely sure how coherent this is, but it is 3am
I guess my nightowl nature is difficult to beat