Ok, there are some examples out there, but they were all lacking the social part (twitter, facebook) and that part is a little different so I thought I'd document that here with a more complete example of populating an ABPersonRef person.

    CFErrorRef err = NULL;
    {
        ABRecordRef person = ABPersonCreate(); // create a person
        ABRecordSetValue(person, kABPersonFirstNameProperty, CFSTR("Hafthor"), &err);
        ABRecordSetValue(person, kABPersonLastNameProperty, CFSTR("Stefansson"), &err);
        ABRecordSetValue(person, kABPersonMiddleNameProperty, CFSTR("-"), &err);
        ABRecordSetValue(person, kABPersonPrefixProperty, CFSTR("Mr."), &err);
        ABRecordSetValue(person, kABPersonNicknameProperty, CFSTR("H"), &err);
        ABRecordSetValue(person, kABPersonOrganizationProperty, CFSTR("Parsus Solutions, LLC"), &err);
        ABRecordSetValue(person, kABPersonJobTitleProperty, CFSTR("Software Architect"), &err);
        ABRecordSetValue(person, kABPersonDepartmentProperty, CFSTR("Software"), &err);
        ABRecordSetValue(person, kABPersonNoteProperty, CFSTR("Line 1\nLine 2"), &err);
        
        {
            ABMultiValueRef emails = ABMultiValueCreateMutable(kABMultiStringPropertyType);
            // string splits to foil spam harvesting
            ABMultiValueAddValueAndLabel(emails, @"hafthor" "@" "parsus.com", kABWorkLabel, NULL);
            ABMultiValueAddValueAndLabel(emails, @"hafthor" "@" "freachable.net", kABHomeLabel, NULL);
            ABMultiValueAddValueAndLabel(emails, @"hafthors" "@" "gmail.com", kABOtherLabel, NULL);
            ABRecordSetValue(person, kABPersonEmailProperty, emails, &err);
            CFRelease(emails);
        }
        {
            ABMultiValueRef phones = ABMultiValueCreateMutable(kABMultiStringPropertyType);
            ABMultiValueAddValueAndLabel(phones, @"480-" "614-9000", kABWorkLabel, NULL);
            ABMultiValueAddValueAndLabel(phones, @"480-" "236-1210", kABHomeLabel, NULL);
            ABMultiValueAddValueAndLabel(phones, @"412-" "HAF-THOR", kABOtherLabel, NULL);
            ABRecordSetValue(person, kABPersonPhoneProperty, phones, &err);
            CFRelease(phones);
        }
        {
            ABMultiValueRef addr = ABMultiValueCreateMutable(kABMultiDictionaryPropertyType);
            {
                CFStringRef keys[] = { kABPersonAddressStreetKey, kABPersonAddressCityKey, kABPersonAddressStateKey, 
                        kABPersonAddressZIPKey, kABPersonAddressCountryCodeKey }, values[] = { 
                        CFSTR("14358 N Frank Lloyd Wright Blvd.\nSuite 15"), CFSTR("Scottsdale"), CFSTR("AZ"), 
                        CFSTR("85260"), CFSTR("us") };
                ABMultiValueAddValueAndLabel(addr, CFDictionaryCreate(kCFAllocatorDefault, (void*)keys, (void*)values, 
                        5, NULL, NULL), kABWorkLabel, NULL);
            }
            ABRecordSetValue(person, kABPersonAddressProperty, addr, &err);
            CFRelease(addr);
        }
        {
            ABMultiValueRef social = ABMultiValueCreateMutable(kABMultiDictionaryPropertyType);
            {
                CFStringRef keys[] = { kABPersonSocialProfileServiceKey, kABPersonSocialProfileUsernameKey, 
                        kABPersonSocialProfileURLKey }, valuestw[] = { kABPersonSocialProfileServiceTwitter, 
                        CFSTR("hafthor"), CFSTR("http://www.twitter.com/hafthor") }, valuesfb[] = { 
                        kABPersonSocialProfileServiceFacebook, CFSTR("hafthor"), 
                        CFSTR("http://www.facebook.com/hafthor") };
                ABMultiValueAddValueAndLabel(social, CFDictionaryCreate(kCFAllocatorDefault, (void*)keys, 
                        (void*)valuestw, 3, NULL, NULL), NULL, NULL);
                ABMultiValueAddValueAndLabel(social, CFDictionaryCreate(kCFAllocatorDefault, (void*)keys, 
                        (void*)valuesfb, 3, NULL, NULL), NULL, NULL);
            }
            ABRecordSetValue(person, kABPersonSocialProfileProperty, social, NULL);
            CFRelease(social);
        }
        // let's add this to the address book
        ABAddressBookAddRecord(addressBook, person, &err); 
        CFRelease(person);
    }