Of course! I just find that a lot fewer of my peers (I am only 20) are bold about their ability to take on big projects than people with a little more life experience behind them.
I've worked with local councillors aged between 20 and 85. All the mediocre ones were middle-aged. ;-)
The Wikipedia user survey found that the median age of people using the site was 22, though the median age increased if you looked at only registered users, and even more if you only looked at administrators. So the Wikimedia community in the UK is probably much younger on the whole than the Board is.
Regarding Chris's point about age limits - I am no expert but I imagine the legal duties of directors mean they need to be over 18?
Chris (The Land)