Running Different Django Versions But Sharing Authentication
A user's login status is stored using sessions. As far as I can tell from comparing trunk to the 0.96 source, the sessions are committed to a cookie the same way, and auth stores the user ID and backend the same way, so as long as the two apps use the same session storage and are on the same domain, it should work. (Just to be safe, I wouldn't use secure cookies in case the backend logic has changed - I didn't check out that part.)
However, 0.96 did not feature pluggable session stores like modern Django does. Probably, to get a current version of Django to work with your 0.96 sessions, you would need to write a session backend for the current Django that connects to the 0.96 database and manipulates the sessions there. I'm not sure how well that would work, though.
Brand new to django. We have a legacy django project using django 0.96x that does authentication, ldap, etc., and it's pretty involved so we don't want to rewrite that code.
We want to add a forum solution (off the shelf) but all of the ones I've seen so far require django 1.x 
I'm trying to figure out how to get this working and I've narrowed it down to the following:

Use an old forum solution that works w/django 0.96 (does this exist?)
Try to patch a forum solution to make it "backwards compatible" with 0.96 (possible nightmare)
Use two different djangos: 0.96 and 1.x and (since we're using Apache w/mod_python) have two different Location directives; adjust PYTHONPATH for each appropriately (or use virtualenv, etc.)

But will option #3 even work? I don't know enough about how django.contrib.auth and friends work so if I run two different versions of django will the user stay logged in? I didn't mention trying to patch our 0.96 project to bring it to 1.x but we don't really have the time to do that.
Any suggestions?