In Zend_Gdata_Extension_RecurrenceException

RecurrenceException.php Line 140:
    public function getSpecialzied()
    {
        return $this->_specizlied;
    }

Here the function name is misspelled, and it returns a further misspelled protected var. The actual protected var is $_specialized (spelled correctly), so this function will always fail.

further down...

RecurrenceException.php Line 151:

    public function setSpecizlied($value)
    {
        $this->_specialized = $value;
        return $this;
    }

This function name is spelled incorrectly (but returns the correct protected variable). This function works, but correcting this error may break existing clients that are using the incorrect spelling.