See http://www.python.org/dev/peps/pep-0294/ for some background on this.  The unexpected thing is actually that the types module still exists at all in Python3 :)

That said, its documentation could, indeed, use some improvement to address this kind of question.

Searching the python-dev email list for 'NoneType removal types module" turns up some interesting posts, back in the 2.3 days...basically, type(None) is the One True Way to get NoneType :)