So based on information here Safari 3rd party cookie iframe trick no longer working? and here Missing cookies on iframe in safari 5.1.5 it\'s clear that old tricks wont work:
I've created working version of fix and uploaded to pypi here: http://pypi.python.org/pypi/django-iframetoolbox
Note: It might not be stable until 0.2 version
I too have created a work around similar to JackLeo's. You can use the middleware or a decorator https://github.com/philroche/django-httpsiframecookiesetter as well as a few more options.