At any given time, one or more architectural disciplines (business, application, technical, information,...) may be applied throughout various phases of a project, which is managed using one or more methodologies within the discipline of project management. I see PM as one of many non-architectural disciplines that are used throughout the course of a project. What I think is missing is something I call Implementation Architecture (which I rely upon) to manage the flow of change used to implement new and/or improved capabilities across the organization. The question raised by Jason is interesting because it calls into question the narrow scope of PPM, which typically only focuses on the portfolio of projects and not the multitude of portfolios across the entire organization (which may be involved in manifesting change). That is where I use Implementation Architecture as the missing architectural discipline within EA to address the structures and relationships between all these portfolios to ensure change is implemented properly once defined by the business and/or operations.
I use Solution Architecture to produce a snapshot of changes that need to be implemented to address (one or more) issues and/or opportunities. Each one of these solution architectures may produce a series of projects, which can impact one or more portfolios within the organization. I use Implementation Architecture to manage these "mini-portfolios" of change and rationalize them against the larger set of portfolios across the organization. Implementation Architecture addresses the complexity of managing change across the numerous Solution Architecture "portfolios" to ensure change flows properly across the organization and the value chain (dealing with multiple domains, multiple dimensions, and even more complexity).