Best practice- How to team-split a django project while still allowing code reusal
Django's componentization of apps means that you can have independent teams working on the various apps, with template tags and filters (and of course, normal Python functions) used for cross-app coupling.
I know this sounds kind of vague, but please let me explain- 
I'm starting work on a brand new project, it will have two main components: "ACME PRODUCT" (think Gmail, Meebo, etc), and "THE SITE" (help, information, marketing stuff, promotional landing pages, etc lots of marketing-induced cruft).
So basically the url /acme/* will load stuff in the uber cool ajaxy application, and every other URI will load stuff in the other site.
Problem: "THE SITE" component is out of my hands, and will be handled by a consultants team that will work closely with marketing, And I and my team will work solely on the ACME PRODUCT. 
Question: How to set up the django project in such a way that we can have:

Seperate releases. (They can push new marketing pages and functionality without having to worry about the state of our code. Maybe even separate Subversion "projects")
Minimize impact (on our product) of whatever flying-unicorns-hocus-pocus the other team codes into the site.
Still allow some code reusal.

My main concern is that the ACME product needs to be rock solid, and therefore needs to be somewhat isolated of whatever mistakes/code bloopers the consultants make in their marketing side of the site.
How have you handled this? Any ideas?
Thanks!