I installed the latest mainline OSGeo4W with all the libs and command-line tools (well, at a minimum, a custom install with with python, gdal and oracle drivers. The oracle drivers (OCI) are not installed by default). Version of python is 2.5 and GDAL 1.8. Dropped a cx_Oracle library in the install folder in order to perform some classical database operations on the Oracle server (10G R2). Then I started scripting.
The OGR OCI driver has several issues, the two main of which: its connection string syntax is a mess and it doesn't support schema's. If I were an altruistic guy I'd delve into the code and arrange this for my fellow coders. But I'm a profiteering bastard in a hurry, lacking time and (most of all) a decent development enviroment (I'm a UNIX man stuck in a Windows suit). So I need quick workarounds.
A connection string that works for OGR (Python 2.5):
ds_str = "OCI:%s/%s@localhost/database:%s" % (user,passwd,tablename) #getting directly the table
A connection string that works for cx_Oracle (5.1 with Python 2.5):
ds_str = "%s/%s@localhost/database" % (user,passwd)
Intrerestingly, using cx_Oracle (5.1.1) in Python 2.7 you don't need to speciy the host, just doing this:
ds_str = "%s/%s@database" % (user,passwd)
Another (minor) caveat: the Python driver won't accept that you specify, on connection, a username and password that are identical. If you're working, like myself, in a environment where this can occur, give the account temporarily a different password (no quotes for either user name or password).
alter user user_name identified by new_password;
After this, you can finally start talking to your server and manipulating your data and geometries in a decent way - using python and OGR.