From a concept persepective, this type of site gets stickier the more upset people get. Which is a good thing, it can be a great place to explore differing opinions and think through your own beliefs, but you have to get people fired up... and Red Sox vs. Yankees is not going to do it. People disagree over which one is better, but there is nothing to talk about. Politics, religion, race, philosophy, Ruby vs. Python, basically everything that ought to make you uncomfortable as a webmaster... and it should, because if you're successful the debates will get ugly in a hurry. But you'll also get that cartoon where the guy doesn't want to go to bed because "someone is wrong on the internet". No one is going to stay up using your site because they've discovered someone prefers the Red Sox.

From a business perspective, in my opinion it's tight. Your CPM is going to be pretty low because you aren't that kind of niche. Probably a few cents. My gut says there isn't much opportunity for acquisition unless it truly takes off. RWW did a roundup I'm sure you saw (http://www.readwriteweb.com/archives/online_debate_sites.php) - you have direct competition from several sides. In my opinion you're competing with more than just those guys... the big poll sites are also indirect competetion, especially for your edge use case settling arguments. Poll Daddy may be your largest, least obvious competition. Data Portability is another... a lot of those types of conversations are happening in Friendfeed and Disqus now, and that trend will only gain momentum.

Routes to success... you have a built in attention base with bloggers - controversy is a major eyeball driver to their sites, and the "blog 2.0" trend - the concept that the blogger doesn't "own" the debate, they just contribute to it, could be leveraged - they will still be inclined to move the discussion over to wordpress, but less snarky about it. If you can find a way to give them what they're looking for (material to write about) you'll get some traction. Otherwise you can try to convince Harrison Ford and Steven Spielberg to debate pink vs. white grapefruit on your site. Good luck :)