import time
currentdate = datetime.datetime.today()
currentdate2 = currentdate.combine(currentdate.date(), currentdate.min.time())
int(time.mktime(time.strptime(currentdate2, '%Y-%m-%d %H:%M:%S')))

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.6/_strptime.py", line 454, in _strptime_time
    return _strptime(data_string, format)[0]
  File "/usr/lib/python2.6/_strptime.py", line 322, in _strptime
    found = format_regex.match(data_string)
TypeError: expected string or buffer

int(time.mktime(time.strptime('2011-06-18 00:00:00', '%Y-%m-%d %H:%M:%S')))

import datetime,time
print time.mktime(datetime.datetime.now().date().timetuple())

>>> time.mktime(time.localtime()[:3] + (0,) * 5 + (1,))
1308574800.0
>>> time.ctime(1308574800)
'Tue Jun 21 00:00:00 2011'
>>>

>>> time.mktime(time.localtime()[:3] + (0,) * 6)
1308578400.0
>>> time.ctime(1308578400)
'Tue Jun 21 01:00:00 2011'
>>>

    currentdate = datetime.datetime.utcnow()
    currentdate = str(currentdate.replace(hour=00, minute=0, second=00, microsecond=00))
    int(calendar.timegm(time.strptime(currentdate, '%Y-%m-%d %H:%M:%S'))