What steps will reproduce the problem?
Python 2.6 + selenium python bindings
>>> from selenium.ie.webdriver import WebDriver
>>> driver=WebDriver()
>>> driver.get("http://www.google.com")
>>> driver.execute_script("alert('test');return 1")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "d:\dev\Python26\lib\site-packages\selenium-2.0_dev_9310-py2.6.egg\seleni
um\ie\webdriver.py", line 439, in execute_script
    value = self._parse_script_result(result)
  File "d:\dev\Python26\lib\site-packages\selenium-2.0_dev_9310-py2.6.egg\seleni
um\ie\webdriver.py", line 424, in _parse_script_result
    raise ValueError("Unknown result type - %d" % restype)
ValueError: Unknown result type - 0

What is the expected output? What do you see instead?
After running this snippet, IE should alert and return value 1. It does alert, but
with no return value, some error occurred.

What version of the product are you using? On what operating system?
Selenium r9310
win7+IE8

Please provide any additional information below.
It seems that there are some bugs within the InternetExplorerDriver cpp module or associated
python module.