Does Django scale?
The problem is not to know if django can scale or not. 
The right way is to understand and know which are the network design patterns and tools to put under your django/symfony/rails project to scale well.
Some ideas can be :

Multiplexing.
Inversed proxy. Ex : Nginx, Varnish
Memcache Session. Ex : Redis
Clusterization on your project and db for load balancing and fault tolerance : Ex : Docker
Use third party to store assets. Ex : Amazon S3

Hope it help a bit. This is my tiny rock to the mountain.
I'm building a web application with Django. The reasons I chose Django were:

I wanted to work with free/open-source tools.
I like Python and feel it's a long-term language, whereas regarding Ruby I wasn't sure, and PHP seemed like a huge hassle to learn.
I'm building a prototype for an idea and wasn't thinking too much about the future. Development speed was the main factor, and I already knew Python.
I knew the migration to Google App Engine would be easier should I choose to do so in the future.
I heard Django was "nice".

Now that I'm getting closer to thinking about publishing my work, I start being concerned about scale. The only information I found about the scaling capabilities of Django is provided by the Django team (I'm not saying anything to disregard them, but this is clearly not objective information...).
My questions:

What's the "largest" site that's built on Django today? (I measure size mostly by user traffic)
Can Django deal with 100,000 users daily, each visiting the site for a couple of hours?
Could a site like Stack Overflow run on Django?