Thinking about KM's Growth as a Concept....

• Knowledge was thought of as an occasional and almost-permanent Thing - Thus were born Repositories
• Knowledge was thought of as something only in People's Minds - Thus were born Expertise Locators
• Knowledge was thought of as a constant Stream of Thought - Thus were born Blogs
• Knowledge was thought of as a Collective Entity (rather than Individualistic) - Thus were born Communities
• Knowledge was thought of as a Constant and Collective Flow & Evolution of Thought - Thus were born Wikis
• Knowledge was thought of as Contextual and Specific to Relationships between People - Thus were born Social Networks
• Knowledge was thought of as that which People Value - Thus were born Social Bookmarking and RSS
• Knowledge was thought of as something that can be extracted, in the form of trends and patterns - from oceans of data and information, through smart/intelligent tools - Thus was born Business Intelligence and Data Mining
• Knowledge was thought of as something that emerges and suggests itself rather than something exists in a ready-to-use form - Thus were born the practices of Brainstorming and After Action Review

Knowledge is not just one of the above but all of it. It has multiple dimensions. Each dimension contributes in its own way towards efficiency and effectiveness. But people, of course, have their own pets and preferences. The culture and specific situation determine what would be the solution's ideal mix.