OK, a few ideas. First, create a page that contains only this:
...and take a look at it. Near the top, "Configuration file (php.ini) path" should be set to "/etc/httpd/conf". If it doesn't, you can't have installed my latest RPMs (build date should be Nov. 10, 2000).
If that's correct, go to /etc/httpd/conf and take a look at php.ini. You're looking for a line that says:
mysql.default_socket = /var/lib/mysql/mysql.sock ; default socket name for local MySQL connects. If empty, uses the built-in
If that line isn't there, or is there with an empty value, that's your problem. If php.ini isn't there at all, that's an even bigger problem, but either problem is most likely caused by a missing or incorrect installation of e-smith-php4.
Next, take a look at /etc/e-smith/templates/etc/httpd/conf/php.ini/80ModuleSettings. If this file (or directory) doesn't exist, you have not installed e-smith-php4-0.3-1 (or -0.2-2), which are required. If the file's there, look for the same mysql.default_socket line I quoted above. There shouldn't be anything editing this file, so this line ought to be there.
If the template file checks out, do /sbin/e-smith/expand-template /etc/httpd/conf/php.ini and then do service httpd restart. Check out the phpinfo page again; it should say that mysql.default_socket is set to /var/lib/mysql/mysql.sock.
If none of this works, post the results of rpm -q e-smith-php4, rpm -q apache, and rpm -q php, and what else you've found, and we'll see what else might be going on.