I’m having the same problem. Running PHP v. 4.3.10 (probably no php problem), mysql v. 4.0.27. on FreeBSD 4.7. The mysql resides at usr/local/mysql and has the database I made for WordPress. I have triple-checked everything else in the WordPress installation steps and can find nothing incorrect.
Yet when I run wp-admin/install.php I get the same message as PB gets:
“Your PHP installation appears to be missing the MySQL which is required for WordPress.”