The site I'd like to model is Nobosh Answers, and their iPhone-specific URL is http://answers.nobosh.com/iphone/
Another great example that actually uses vBulletin is found at the iLounge forums: http://forums.ilounge.com/index.php?styleid=7 - Unfortunately, I've contacted them and they are not willing to share their style.
The key difference between the themes from iLounge and iPhorum is that iLounge is actually designed to work well with the iPhone's finger-pointing UI and formatted to be easily readable on an iPhone without zooming in.
I'm going to tackle this myself and make it available to anyone interested. Anyone have any suggestions before I get started?