[Brian]

Sorry for the trouble this is causing, Patrick! If you look at the "Creating a computer-to-computer network" page in Mac help, and then use those steps to connect your iPhone and your Mac, is OmniFocus able to sync? (Please quit and restart both copies of OmniFocus after setting up the ad-hoc wireless network, and then try the sync.)

That will help us isolate problems caused by some misconfiguration in either copy of OmniFocus (if the problem persists) from problems caused due to the configuration of the larger wireless network (if it doesn't).

Once we have a better idea of where the problem resides, we can suggest possible solutions.