Given that they have >22k subscribers already, the chances of actually getting to say something in your lifetime are pretty low - assuming nobody else joins and there are no repeats, it would take over 60 years for everyone to get to post once.
That said, it sounds interesting, as a "15 minutes of fame lottery" at least.
It's well worth it for the range of people and emails. It adds a little spice to every day, and usually gives you something to think about. A little peak into how crazy different everyone lives their lives. It doesn't really matter to me if I'm never picked. In fact, I probably wouldn't want to be picked...
That said, it sounds interesting, as a "15 minutes of fame lottery" at least.