I'm a little shocked by the recent amount of time being devoted to little kids in preschool and kindergarten. Who would have thought kids 7 and under would be written about so much? Of course, I'm only furthering "the cause" by writing about it, so my apologies for that.
Joanne Jacobs had an interesting blog post on old kindergarten students and "red shirting", which I find amusing because of its ties to football. I read red shirting in these education articles and think of little 6 year olds in pads and a helmet.
So what's my take on the matter? In spite of what most people are saying about older kids having the advantage, I'd disagree but probably only because my situation was quite the opposite. I skipped 2 grades, was always the youngest in my grade, and I did very well in school. Age wasn't an issue for sports or social reasons either, though sometimes it was trying (such as when I didn't get my license until senior year of high school). Anyways, age wasn't a problem in college either.
My advice would be to just put your kids in school, give them the tools they need to succeed, and then try to get out of their way. But writing (and reading) the endless articles on what to do with 6 year olds isn't going to solve any parent's anxiety - that's an issue they need to work on themselves.
Parents need to be there to support their kids, but not be too involved because then they end up stifling their kid's independence and creativity. And if you don't think kids then become too reliant on their parents, I've read many articles about "helicopter parents" who hover over their kids activities far too much - there was one story I read about how a new analyst out of college wasn't happy with something at his job so his mom called in to work to complain!