How to open OSM file in Python with GDAL

I am trying to open a *.osm file in Python with GDAL. But I doesn’t work. What am I doing wrong?

import ogr
driver = ogr.GetDriverByName('OSM')
datasource = driver.Open('map.osm')
layer = datasource.GetLayer()

Error looks like this

>>> 

Traceback (most recent call last):
  File ".../osm_reader.py", line 3, in <module>
    datasource = driver.Open('map.osm')
AttributeError: 'NoneType' object has no attribute 'Open'

I exported the data directly from the OSM Website.
My Python Version is 2.7.5.

About my GDAL Version I am not sure. And this might be the problem.

Easy Install says

U:>easy_install GDAL
Searching for GDAL
Best match: GDAL 1.10.1
Adding GDAL 1.10.1 to easy-install.pth file

Using c:python27libsite-packages

GDAL Version says

>>> gdal.VersionInfo()
'1810'

Does 1810 mean GDAL 1.10.1? How do I get this to work?