I followed this solution to including Wordpress functionality within ZF: Zend Framework and Wordpress integration
Specifically this code:
define('WP_USE_THEMES', false);
require_once 'wp-blog-header.php';
I've stepped through the debugger and everything seems to run smoothly, it runs through the is_blog_installed() wordpress function a few times, but then all of a sudden decides the blog is not actually installed and takes me to the "Wordpress is already installed" screen.
Let me know if any files might help in resolving this.
Cheers Ant