As not all of us are willing to let go ZF for Symfony, the native environment for Doctrine, here is a clean way of integrating Doctrine 2 into your ZF projects.
As the integration method chosen was to create an application resource, you may enable both new projects and existing ones to use Doctrine 2 without changing a single line of bootstrap code.
Added bonus – memcache integration and a custom Doctrine 2 eAccelerator caching class which I strongly advice against using, at least on Windows 
Requirements:
- PHP 5.3
- ZF 1.10.5 or compatible
- Doctrine 2.0 beta 2 or compatible
- Memcache (optional, available on Windows too)
- Some of the attached source code