Seems Mountain Lion removed the default paths to enable the 'Sites' directory for web access in Mountain Lion (10.8).
They still included Apache - so easy enough to bring back to norm.
Create a configuration file with your username as the filename such as:
/etc/apache2/users/rweeks.conf
File contents:
<Directory "/Users/rweeks/Sites/">
Options Indexes MultiViews
AllowOverride None
Order allow,deny
Allow from all
</Directory>
Then simply restart apache and the dir will be restored:
% sudo apachectl restart