Can an Architect be an effective Project Manager as well?

When you look around in the job market, you see job postings that require both Architectural and Project Management expertise. Typically these postings are from companies that don't have an established architecture practice but that recognize the importance of architecture.

The question that comes to my mind is, 'Can an architect be an effective project manager as well?’ From what I understand, after having worked as an architect and after having dabbled with project management, the general attitude of the practitioners within these fields is very different. As an architect, you are trained to abstract complexity, and to only delve into details that are architecturally significant. As a project manager, you are required to delve into the lowest level of detail and to work out their dependencies.

Maybe there are projects of a certain scale where having an Architect/Project Manager works out to be more cost effective.