For what it's worth, Debian added PDO when they updated to PHP 5.2.0 in Unstable, citing PHP 5.1 as "deadware" upstream. See the end of <a href="http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=348882">bug 348882</a>. The PHP website itself says that 5.2.0 "obsoletes the 5.1 branch of PHP."
-- Cannot install PDO and PDO Drivers in PHP5 https://launchpad.net/bugs/50353 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs