If I remember correctly, there are a few feature requests for the ability to import appointment information from iCal into OmniFocus, but off the top of my head, I'm not aware of any AppleScripts that do so. (There are a couple of AppleScript-related posts in the
iCal Syncing forum - it's possible that one of the scripts there could be adapted to do this, if you want to give it a try.)
If you email the Support Ninjas, we can attach you to the feature request in question - by doing so, you help that request move up the priority list. (All other things being equal, a more popular request will get assigned higher priority.)