Not exactly. I am under 18 and have found no easy way to make my way around their age requirement. Your age is tied to your Google Account from the moment you created it and there is currently no way to ever change it.
Why would you ever choose to put your real age? Until I was over 18, my age on most websites was around 90.
Why wouldn't I? Plus, Raphael suggested that Google's action would lead to people lying about their ages - which hinted that their was a way for people to change their ages on their Google accounts after the fact. I was simply responding to that question.