I haven't participated in any contests yet but I do plan to this time around. I didn't participate in the last one, because creative writing is something that would need extra work for me, and there was no way I could get up to speed to actually win anything. I had plenty of other topics I preferred to write about.
This time, we are given two months to write a hub or more. We can answer any question, so the topic is very open as well.
For those who were unaware of the contest, I think HubPages does all they can to announce a contest. The contest link is in the black bar at the top of the page. There is also a topic in the forums, a blog post, and it is mentioned in the newsletter. Some hubs have also mentioned it.