Hi Trinh,
It's true that django-auth-ldap 1.1 dropped support for Django < 1.3. However, this doesn't necessarily mean that it doesn't work, only that it's not supported. I try to be conservative in the changes that are made to maintain maximum compatibility. However, I'm only willing to maintain so many virtualenvs for testing, so I only tend to officially support more recent versions of Python, Django, and python-ldap. The burden for maintaining deprecated dependencies falls on those who use them. I'm generally happy to take fixes for old library versions as long as they're simple and don't threaten forward-compatibility.
I just installed django-auth-ldap 1.1.2 with Django 1.1.4 in Python 2.7 and all of the tests pass. It will probably work just fine for you. You may just want to be more diligent than usual in testing your deployment and more cautious than usual in taking updates.
Thanks,
Peter