English: Capability management (Photo credit: Wikipedia)

I think of IT Architecture Capability as the combination of people (their competencies and skills, regardless of their team names or job titles), methods, information and supporting tools that allows an organization to consistently produce IT products with a fit-for-purpose architecture, cost effectively.

I believe that Architecting IT solutions that are fit for purpose is an important business capability in many enterprises. Not strategic, in most cases, but definitively important. It needs to be done well, and it needs to be done cost effectively.

Being a business capability, I would argue that the architecture practice of an IT organisation should be run like a business, competing with other business capabilities (marketing, operations, sales, etc) for organisational resources to generate value that exceeds the cost of capital. As such, traditional technical competencies are necessary but insufficient to be successful. An organisation designing the best cars in the works, will fail without supporting competencies in marketing, production, performance measurement, supplier management, quality, and many other disciplines.

Ultimately, to be successful, an architecture practice needs to provide to its stakeholders (within and outside IT) what they need, cost effectively. Worth repeating: to be successful, your architecture practice needs to provide to your stakeholders what they need at a reasonable cost.