Actually, even this leaves a loose end or two... the mysql.so php extension is not available if these directions are followed as is, and it cannot be built when building php from source either. Apparently the version of mysql in the repository for ubuntu 10.04 is not compatible with php 5.2.x as far as building that extension is concerned anyway.. I'm guessing the solution to this is to build mysql from source as well.
Interestingly enough, drupal 7 DOES work without that extension enabled, but phpmyadmin will not, nor will drupal 6. Apparently something in the new drupal 7 db class is smart enough to leverage PDO in ways these others cannot.