Get current datetime with timezone and microsecond precision

datetime.php

<?php

/**
 * Generate datetime with timezone support and microsend precision.
 * 
 * Example:
 * ```
 * $now = Datetime::now(); // generates YYYY-MM-DDTHH:MM:SS.MMMMMM
 * ```
 * 
 * @author John Fragkoulis <john.fragkoulis@gmail.com>
 **/
class Datetime
{
  public static $defaultTimezone = 'Europe/Athens';
  public static $defaultFormat = 'Y-m-d\TH:i:s.u';
  
  public static function now($format=null, $timezone=null)
  {
    $format = $format ? $format : static::$defaultFormat;
    $timezone = $timezone ? $timezone : static::$defaultTimezone;
    
    $datetime = date_create_from_format('U.u', microtime(true));
    $datetime->setTimezone(new DateTimeZone($timezone));
    return $datetime->format($format);
  }
}

Supported by PHP 5.3 or greater