This is probably the best explanation to DevOps from the Ops perspective, what it is and what it is not. If you are trying to understand how you or your organization can get from where you are now to ultimately a DevOps model and philosophy this will help you understand that.
I also think it is a good primer for all levels of an organization within IT (C-suite, directors, managers, and engineers) to understand how each contributes to the success of getting to a DevOps model for your organization.