Sorry, just noticed the other iphone fourm and this answer:
Hi willhains,
WebDAV is built into Mac OS X Leopard ... more or less.
You can activate WebDAV on your Mac (tutorial:
http://manas.tungare.name/blog/2008/...cus-to-iphone/) and then sync both your Mac version of OmniFocus and your iPhone version with this WebDAV server.
Hope that helps
regards
Boris
P.S.: The tutorial seems to be explicitly for OmniFocus users.
Edit:
P.P.S.: That will only work over (W)Lan ... I don't think that there's a way of syncing through the sync-cable.