#!/usr/bin/env python

import datetime

def hrdd(d1, d2):
    """
    Human-readable date difference.
    """
    _d1 = datetime.datetime.strptime(d1, "%a %b %d %H:%M:%S %Y")
    _d2 = datetime.datetime.strptime(d2, "%a %b %d %H:%M:%S %Y")
    diff = _d2 - _d1
    return diff.days # <-- alternatively: diff.seconds 

if __name__ == '__main__':
    d1 = "Mon Jun 28 10:51:07 2010"
    d2 = "Fri Jun 18 10:18:43 2010"
    d3 = "Wed Dec 15 09:18:43 2010"

    print hrdd(d1, d2)
    # ==> -11
    print hrdd(d2, d1)
    # ==> 10
    print hrdd(d1, d3)
    # ==> 169
    # ...

>>> import datetime
>>> a = datetime.datetime.strptime("Mon Jun 28 10:51:07 2010", "%a %b %d %H:%M:%S %Y")
>>> b = datetime.datetime.strptime("Fri Jun 18 10:18:43 2010", "%a %b %d %H:%M:%S %Y")
>>> c = a-b
>>> c.days
10