As per the subject - is there an API to get the MCC/MNC on iPhone OS 2.1 or above?
No, mobile network information is not available through the API. If you're looking for a unique device ID, take a look at UIDevice's uniqueIdentifer method; if you're looking for the country the device is in, you need Location Services; if you want a good indication of the user's home region, take a look at NSLocale; for anything else, just ask the user.