probably worth linking to this http://drupal.org/project/uc_civicrm though my understanding is that this module takes an address from ubercart and pushes it into civicrm for storage, in my ideal the user would actually be entering info into civicrm and ubercart would be pulling it out of there. That way if you have a user who's address is already in civicrm (from a mailing list import or member list import) they can choose their address, or update right there in ubercart.