You may have already tried these, but just in case:
make sure at least one context has been dragged out of the "unsynchronized" group in OmniFocus' preferences and dropped on one of your iCal calendars. If all of the contexts appear in "unsynchronized", that's why nothing is showing up in iCal.
Next, make sure you're checking the iCal todo database; we don't sync with the calendar database, so actions will not show up in the calendar view. Select View -> Show ToDo list... in iCal.
Last, try checking the "Add blocked actions to calendars" box in OmniFocus' preferences.
If things still aren't showing up in iCal, contact the
support ninjas so they can help.