Nice article. I use virtualenv heavily and still do the symlinking dance. I keep my django trunk in a ~/libraries folder and symlink the django folder to the /path/to/virtualenv/lib/pythonX.X/site-packages folder. I'm not sure that I have a compelling reason for doing so.
It feels better than symlinking to me.
I would really only do this if I had a custom patched django though. If speed/bandwidth is a concern, just make sure your pip cache is setup properly.