Filesystem management for multiple installations/upgrades

I will be hosting the roundtable on filesystem management for multiple installations/upgrades.
Things can be controlled at various levels: httpd.conf, .htaccess, DocumentRoot (symbolic links to different versions of Drupal, different vhosts), and by Drupal at various stages. There’s more than one way to do it, and sometimes I don’t get the results I expect.

I will bring a laptop and let’s see if we can break things :-)

This is pretty much a repeat of the blurb from the roundtable. I will be happy if it gets some discussion going, but equally happy if it just sparks some thoughts for the actual event.