According to this interview:
Mayor Ray Nagin has purchased a home for his family in Dallas and enrolled his young daughter in school there. ...[he] said he planned to return to New Orleans on Saturday. He said he will remain in the Crescent City while his family lives for the next six months in Dallas, making occasional visits to his family when possible. It's not clear where Nagin will be living: His home along Bayou St. John suffered massive flooding, the mayor said, although he has not inspected it...
UPDATE: NOLA has since issued a correction: "Nagin renting Dallas condo, did not buy house".