Converter um carimbo de data / hora Unix em tempo em Javascript

/**
 * Convert a Unix timestamp to time in Javascript
 * See http://stackoverflow.com/questions/847185/convert-a-unix-timestamp-to-time-in-javascript
 * @param int unix_tm Unix timestamp in seconds from for instance PHP
 * @return date timestamp in milliseconds
 */
function dateFromUnixTimeStamp(unix_tm) {
    return new Date(unix_tm*1000);
}

Cortesia de Aron Rotteveel no Stackoverflow
http://stackoverflow.com/users/11568/aron-rotteveel

Obrigado @thajeztah