There are a couple of things I would like to point out that you may already realize:
1) It is extremely important that for something like this to succeed you must concentrate on keeping the level of discourse as high as possible, not unlike HN. The minute I see someone posting "you're an idiot" without an actual argument that's going to turn me off.
2) I'm not a big fan of the two goals you have listed on the home page- "stand up for what you believe and meet like minded people." The reason I say this is because when I come to a site to learn about a political or social issue, I come to not only express my opinion but learn about others as well. "Without fully understanding your opponents argument, you can't fully understand your own." My goal is probably not going to be to find like minded people as that is who I have surrounded myself with on a day to day basis for the most part.
Great idea though and good luck to you.
If you want to sign up, here's a link for the first few hundred HNers: http://www.twosides.co/register/hackernews
Here's an example more related to the tech crowd: http://www.twosides.co/issues/22-the-best-tech-ceo-after-ste...
If you just want to learn more: http://www.twosides.co/
If you'd like to get in touch privately, just email hello@twosides.co
My main feedback is that all of the information looks equally relevant on the page. I would suggest minimization of suggestions of other debates and focus the UI on debating the current issue you are looking at. It seems that you want people to debate rather than just vote. As of right now, I get lost in the three column layout.
Another shift to consider is having the evidence before the voting. If your goal is to educate and to encourage discuss over voting, the information on positions should be more readily available.
No doubt this vertical is hard to design for, ha ha
