web sharing on lion - odd behavior
The permissions of some folders did change to more restrictive on Lion. I don't know about 10.6, but /Library/WebServer/Documents/ is owned by root and has 751 permissions on 10.8 as well.

I don't have any postrgesql folder by default on 10.8, but 10.7 might have had one.

Files are normally meant to put be to ~/Sites/ and accessed from http://localhost/~username/. The URLs can be made shorter by adding virtual hosts.

You could change the owner back to yourself with sudo chown -R $USER /Library/WebServer/Documents/.