What is the role of a Enterprise Architect in a programme?

This post on CIO Knowledge Base explains how an enterprise architect is not needed if enterprise architecture is present and a manager is simply trying to ensure that a new project will fit with the existing architecture. On the other hand, if the project involves changes a scope of the enterprise architecture, then managers will have to consult with the enterprise architect. Program managers have the ability to monitor implementation of enterprise architecture as long as no changes needed to be made to the infrastructure itself. How does your company define the role of an enterprise architect in a progamme?