My iCal stopped syncing with my iPhone 5 and my iPad --- and after HOURS of reinstalling the OS the same problem persists!! I've check my original post via communities and still no response at all. Bummer.
iCal won't sync with devices; however appointments I post on my devices sync to each other and to iCloud. Its ONLY iCal that has the problem!
And since reinstall of OS, I now have 2 of every contact on my computer too!