I finally got iCal syncing to work! The support ninja's asked me to reset sync services. Here's the email I received. Hope it helps someone else.
"Hm...I'm not sure what could be causing that. You may want to try resetting Sync Services:
http://support.apple.com/kb/TS1627
There is another way that OmniFocus interacts with iCal that you may find useful. If you're synching OmniFocus through a WebDAV server, you can use the calendar subscription feature to publish iCal events from OmniFocus. Each time you sync OmniFocus with your sync server, any upcoming due events will be published to an .ics calendar file stored on your sync server, which iCal on your Mac or iOS device can subscribe to.
If you're not currently synching via MobileMe or WebDAV, you can sign up for our free server at <www.omnigroup.com/sync>. Once you've set up your account, go to <sync.omnigroup.com>, sign into your account, and click the "Send to OmniFocus" button to import your sync settings into OmniFocus.
Once you set up synching in the Sync Setting screen, click the "Publish Due reminders as a calendar" checkbox, then click on the Subscribe in iCal button. From there, iCal should show your upcoming due actions (anything due within the next two weeks) in OmniFocus as calendar events."