I worked out what it was since I opened this thread: there were two issues that I would have thought would crop up in any vanilla LAMP setup installed according to the Media Temple Knowledgebase article (which was what I used to set up the (ve) server).
Firstly, it was the rewrite module. It appeared as though my .htaccess files weren’t being read by the server because a rewrite module has to be enabled: this seems to be the default on a fresh install such as the one I just carried out. Who knew?
Enabling the module is pretty simple: I just needed to make a symbolic link to the rewrite.load file from the mods-available directory to the mods-enabled directory (all found, in this instance, in the apache2 directory, at /etc/apache2).
Ran the following:
cd /etc/apache2/mods-enabled
ln -s /etc/apache2/mods-available/rewrite.load rewrite.load
Secondly, I concluded I also need to change all instances of AllowOverride in /etc/apache2/sites-available/default (which are all set to None by default) to All(see this article which explains the issue).
Finally was the question of how to apply the rules. I actually chose to delete my .htaccess file and place all its rules in a <Directory> section in http.conf (which is now a separate file still called in apache2.conf, and which I'll use to include all my customizations), because setting AllowOverride to None and relying on apache2.conf for everything induces an increase in speed as the server no longer has to check for an .htaccess file at every level before loading a page. I then deleted the .htaccess, set AllowOverrideto None, and the rules still loaded fine.
/etc/apache2:sudo /etc/init.d/apache2 reload(if this fails, tryrestartinstead ofreload) – Lekensteyn Dec 10 '11 at 10:17.conffiles take effect immediately? Rebooting the whole server doesn't do it either… – Donald Jenkins Dec 10 '11 at 10:28