Some parts of the country, including major cities like Boston, only get updated satellite imagery from Google every 3 or so years.
For Fresno, it’s never more than a year before we get the freshest pictures. The latest update, rolled out last week, shows Fresno and the surrounding area as of March 15, 2013.
That’s less than 7 months between updates! Older images are still accessible via the history slider in Google Earth.