I've recently "activated" the web sharing in OSX 1.8 « Mountain Lion ». It works well with PHP & HTML. But I stuck with 403 errors with images (jpg, png).
Do you have any idea why ?
So as I said in the comments above, the problem was that only the owner of the file did have the rights to read the file.
A simple chmod +r on the file solved my problem.
Have a look at /var/log/apache2/error_log and try to identify your problem. I had :
[Fri Aug 31 13:31:20 2012] [error] [client ::1] Options FollowSymLinks or SymLinksIfOwnerMatch is off which implies that RewriteRule directive is forbidden: /Users/myname/Sites/
in my /etc/apache2/users/myname.conf i've replace
Options Indexes MultiViews AllowOverride All Order allow,deny Allow from all
Options Indexes FollowSymLinks MultiViews AllowOverride All Order allow,deny Allow from all
That just add FollowSymLinks in Options.
and it was great for me ...