Migrate Module and AddressField Locality/City Lookup in PrepareRow Fails
Found the issue.  When using the addressfield module, you should have field mappings that allow for preparerow to work.  I thought that the address_arguments array was enough to create the field maps.  Also I was using the csv column title 'Zip' instead of the the mapped field title 'postalcode'

Under my address field mapping I added the following code.

    $this-&gt;addFieldMapping(NULL, 'fname');
    $this-&gt;addFieldMapping(NULL, 'lname');
    $this-&gt;addFieldMapping(NULL, 'address');
    $this-&gt;addFieldMapping(NULL, 'city');
    $this-&gt;addFieldMapping(NULL, 'state');
    $this-&gt;addFieldMapping(NULL, 'postalcode'); 


I also moved the function zipcity to my helper function file to allow other migrations to use it if needed.

This post https://drupal.org/node/1326044 was key into figuring out the missing link.