PHP 5.1.3 was just released, including the latest PDO and PDO drivers. If you're still running older releases of PHP you should probably upgrade. If you don't want to upgrade the PHP core then you'll be pleased to know that I've also released the PHP 5.1.3 versions of PDO, PDO::MYSQL, PDO::PGSQL, PDO::SQLITE and PDO::ODBC to PECL--these are the versions that I've had time to personally test.
These are identical to the code in PHP 5.1.3, with the exception of PDO::ODBC, which includes two additional bug fixes that didn't make it in time.
He also shares a note for those out there trying to build PDO drivers off of the older PECL drivers to work in PHP 5.1.2. Unfortunately, they were also filing bug reports when things broke - a thing that "doesn't make sense" when the bundled PDO should work just fine.