I've been thinking about this.
The fact is, we probably should *not* be automatically trying to determine the URLs.
It would be nearly trivial to have people add it to their base URLs, and then we get:
1) Faster startup
2) More compatibility with "the way things are done" in standard Django apps.
3) More clarity
4) (most importantly to me) No possibility of people accidentally enabling test mode in live stores.
In a live store, this stuff should be set in stone, we don't get a lot by auto-determining the URLs. Thoughts?