Nice forum. It looks like the Yahoo ads are pretty targeted so I'd imagine you'd be getting a decent-ish CTR with them. If the CTR is low, try getting the AdSense/YPN plug-in for vBulletin -- it allows you to place ads inbetween the first and second post of a topic. It really does boost CTR and isn't all that obtrusive. I can't really find any faults with your forum. It all looks very clean and you should do well with proper marketing and SEO. Best of luck!
Fantastic logo - definitely A+. The look of the site is super sharp and clean, very impressive. From a seo perspective, you aren't taking advantage of the H1 tags where you can gain rankings for the keywords you want to rank for. Also, offload all your css to it's own folder. The search engines don't process that code and it's just more useless information in the way to getting to your site content.