Is everything greater than None?

None is always less than any datatype in Python 2 (see object.c).

In Python 3, this was changed; now doing comparisons on things without a sensible natural ordering results in a TypeError. From the 3.0 "what's new" updates:

Python 3.0 has simplified the rules for ordering comparisons:

The ordering comparison operators (<, <=, >=, >) raise a TypeError exception when the operands don’t have a meaningful natural ordering. Thus, expressions like: 1 < '', 0 > None or len <= len are no longer valid, and e.g. None < None raises TypeError instead of returning False. A corollary is that sorting a heterogeneous list no longer makes sense – all the elements must be comparable to each other. Note that this does not apply to the == and != operators: objects of different incomparable types always compare unequal to each other.

This upset some people since it was often handy to do things like sort a list that had some None values in it, and have the None values appear clustered together at the beginning or end. There was a thread on the mailing list about this a while back, but the ultimate point is that Python 3 tries to avoid making arbitrary decisions about ordering (which is what happened a lot in Python 2).

From the Python 2.7.5 source (object.c):

static intdefault_3way_compare(PyObject *v, PyObject *w){    ...    /* None is smaller than anything */    if (v == Py_None)            return -1;    if (w == Py_None)            return 1;    ...}

EDIT: Added version number.