Home prices are up by the biggest margin in nearly seven years.  The latest S&P/Case-Shiller index shows a 9.3% jump year over year for the month of February, which beat analyst expectations in the 20-city survey.  The Phoenix market showed the biggest gains, where home prices are up 23%.  S&P Committee Chairman David Blitzer says housing continues to be a bright spot in the economy, despite mixed economic reports for the month of March.