I was one of these kids. I started kindergarten at 4, and then later skipped 8th grade. This put me in college at the ripe old age of 16 as well. I still stand by that, even though I am now wishing I'd taken a bit of time to smell the roses before entering college.

I was a royal terror in pre-school, until one day I wandered over to the older-kid table and they realized that I was bored to tears. I was maybe 2.5 or 3 at the time, but this prompted my parents to get me tested to enter kindergarten early when the time came. I was accepted, and went, and I really do not think it made one bit of difference. I definitely think that I enjoyed school more because I was actively engaged and learning.

Skipping 8th grade was a different matter for me. In retrospect, I still would have done it, because academics have always been more important to me than having a social life, but I really felt out of place in high school and I haven't felt quite right since. I really don't know that I noticed the social aspect of school up until middle school, so I wouldn't say that was an issue for me when starting kindergarten early.