kidtreo —
Make sure no firewall rules are blocking network traffic between your iPhone and your Mac. (If things don't seem to be working, try turning off the firewall temporarily.)
System Preferences > Security > Firewall > Allow all Incoming Connections
Once you've disabled the firewall, try restarting both devices and reconnecting to the Ad Hoc network you've got set up.
If that doesn't help, our ninjas are poised to assist you in troubleshooting this via phone or email —*please don't hesitate to contact us.
omnifocus@omnigroup.com
800-315-OMNI