Tapatalk (or a similar service/product) would be the best solution. It's a free plug-in for vBulletin, and on the phone-side, supports iOS, Android, Blackberry, and Nokia. The iOS and Android apps are $3, but that allows you to also browse and post on any other Tapatalk-enabled forum (if you're a member of them).
I don't know if it supports the version of vB that CD is running now, though.