Definitely not a contest.
As Lynn says, it's intended to give everyone a view of members who are new. So when you see a new member you know they are new.
My intention is to change this to not show a number, but instead show a little button that indicates your participation status. Those who have only posted 5 times, for example, get a little seedling graphic, then when you've posted more your graphic becomes a large plant and finally a mature tree. Or something like that.