php-pecl-pdo-devel conflicts with php-devel thus making installation impossible. Also php-pecl-pdo is allowed to be installed at the same time as php-pdo (thus overwriting the /usr/lib/php/modules/pdo.so) this package should Provide: php-pdo so it will replace it, or just not make this package available and update the php-pecl-pdo-sqlite package to use php-pdo/php-devel packages.
I've just discovered that FC's PHP 5.1.3 has php-pdo and includes the PDO extension, as well as the sqlite one. The solution here seems to have the "php-pecl-pdo*" packages removed and php-pdo to obsolete them.
The obsoletes were already in place, I just hasn't been notified about it. The packages have now been removed, so all you need is php-pdo and php-devel from now on.