SurveyUSA released a presidential poll for Georgia on October 13. The results: McCain 51%, Obama 43%, other 4%, undecided 2%. Barr is the only “other” choice on the ballot, but write-ins are permitted.
The same polling company released a similar poll two weeks ago, which showed “Other” at only 2% in Georgia. See here for the current poll, which is broken down by interesting demographic characteristics.