you can use a string formatter to pad any integer with zeros. It acts just like C's printf.
>>> d = datetime.date.today()
>>> '%02d' % d.month
'03'
Updated for py36: Use f-strings! For general ints you can use the d formatter and explicitly tell it to pad with zeros:
>>> d = datetime.date.today()
>>> f"{d.month:02d}"
'07'
But datetimes are special and come with special formatters that are already zero padded:
>>> f"{d:%d}" # the day
'01'
>>> f"{d:%m}" # the month
'07'