_GET and _POST should not be consulted when retrieving request parameters in a front-controller, routed system.

@see http://nabble.com/Params-and-Post-vars-tf4075463.h…

I have a proposed fix:

In http request:
    protected $_paramSources = array('_GET', '_POST');
    
    public function setParamSources(Array $paramSources = array())
    {
        $this->_paramSources = $paramSources;
        return $this;
    }

    ... 

    // changes to getParams getParam
    public function getParam($key, $default = null)
    {
        $keyName = (null !== ($alias = $this->getAlias($key))) ? $alias : $key;

        if (isset($this->_params[$keyName])) {
            return $this->_params[$keyName];
        } elseif (in_array('_GET', $this->_paramSources) && (isset($_GET[$keyName]))) {
            return $_GET[$keyName];
        } elseif (in_array('_POST', $this->_paramSources) && (isset($_POST[$keyName]))) {
            return $_POST[$keyName];
        }

        return $default;
    }

    public function getParams()
    {
        $return = $this->_params;
        if (isset($_GET) && is_array($_GET) && in_array('_GET', $this->_paramSources)) {
            $return += $_GET;
        }
        if (isset($_POST) && is_array($_POST) && in_array('_POST', $this->_paramSources)) {
            $return += $_POST;
        }
        return $return;
    }

This also needs to be set as a FrontController parameter, since request creation happens at dispatch time.

But i think you know what to do.