[Ken Case]

There's a sample "Publish to iCal" script which runs through all your contexts and creates a new calendar for each one (named "OF: [Context]"), adding any available tasks from that context to that calendar.

The script ships with every copy of OmniFocus: you can find it by Control-Clicking on the OmniFocus app in the Finder, choosing "Show Package Contents" from the contextual menu and navigating into Contents/Resources/SampleScripts.

It wouldn't be difficult to modify the sample script to publish all the tasks into a single calendar instead, or into a specific calendar (such as your default iCloud calendar)—or to create events in iCal rather than "to do"s.

Hope this helps!