I’ve had a similar issue a couple times and renaming the file did not work for me. With OS X Lion I found the right configuration is this:
<IfModule php5_module>
AddType application/x-httpd-php .php
<FilesMatch \.php$>
SetHandler application/x-httpd-php
</FilesMatch>
AddType application/x-httpd-php-source .phps
<IfModule dir_module>
DirectoryIndex index.php index.html
</IfModule>
</IfModule>
The magic that made it work for me is the SetHandler application/x-httpd-php
part.
Of course edit the <IfModule php5_module>
to your php version.