Update: Some Curious User brought to my attention, that a ticket has been opened which, when implemented, will add a setting for a cache prefix. It will also allow other cache key manipulations. Django has implemented Django 1.3 has implemented KEY_PREFIX in the development version, which currently means, that it will be out in 1.4 iirc.KEY_PREFIX which solves the problem once and for all.
Until recently I’ve been using the file:// django cache, but that has a “problem” when multiple users needs to manipulate the cache (think uid 80 writes a key, that uid 1000 wants to delete).
My problem with the memcached:// django cache provider has been, that it cannot handle being used on a shared memcached instance, because of the danger of key collissions.