Never heard of it.
I wanted to do it a few years ago, but couldn't get a team together. I think the idea is really cool, but it can be really challenging. I'd say you can learn a lot and it'll help your AI skills, but realize that in order to get a lot out of it, you have to put a lot into it.
The 2013 competition is still open. I've just registered, and am checking out the info now. Seems like it could be fun.
The problem is the deadline is for less than a month. And it is indeed very challenging. Just reading the rules and understanding them well might take that time. Most contestants have probably been preparing since last year. :/
The problem is I don't know how much I can put into it xD
But it really feels like it will scratch that itch I've been having for AI. I just don't know if something else might better.