blewis: that sounds like a bug, please be sure to report it to
omnifocus-iphone@omnigroup.com.
santra: The iPhone version of OmniFocus does understand repeating tasks even though there's no way to set them up on the phone itself. (Just as the Desktop understands that contexts have geo locations even though you can currently only set those locations on the phone.) This might be getting a little technical, but the model code is all shared between the desktop and the phone; the only differences are in the interface code.