Qiang,
FirePHP itself allows logging of array data. In the log it shows array contents.
I suggest to modify CLogger to check if log message is array and if it is then convert it to string using print_r($arr, true);
What do you think?
public function log($message,$level='info',$category='application')
{
if (is_array($message)) $message=print_r($message,true);
$this->_logs[]=array($message,$level,$category,microtime(true));
}