The point about “no one-size-fits-all/no single technology” is crucial – KM is a combination of business objectives, process, culture, organizational development, technology, etc… I consider the “people” piece of it as (a lot) harder than the technology or business piece.

You can also look at KM systems in terms of how well they support tacit (in your head) vs. explicit (in a tangible form such as documents) knowledge.

Tacit knowledge can be supported by encouraging open and collaborative (though perhaps less structured) forums such as mailing lists, threaded discussions, and communities where you can find subject matter experts.

Explicit knowledge can be much more scalable in terms of how it can be shared and leveraged across the organization.

So I think that KM in an organization should support tacit knowledge sharing, but the chief aim should be to continuously encourage the people to share their knowledge explicitly.