Zend_Db allows an 'adapterNamespace' to be specified. This would allow us to remove core/Db.php (Piwik_Db::factory) and go back to using Zend_Db::factory.
Changes:
Remove:
Update script:
Let's not change this for now. The extra abstraction may help others in porting Piwik to other databases (e.g., Postgresql).