For the past year, I've been running change management plans parallel to the project plans. Although this isn't an ideal situation, I think it's a natural and necessary evolution to an integrated technical/change plan, because an organization needs to see and understand exactly what a change plan is. It's not an easy concept for most business managers or project managers to wrap their heads around, so once they understand and see it, it's much easier to integrate it with a project plan.
I'm at the stage where I am working with the head of our Project Management office to integrate the plans and I will be training the Project Managers on their role and how they need to incorporate change plans into project plans.