According to this Line-56 article:
AMR mentions that Cisco is using wikis and blogs for IT change management, project tracking, and documentation; executive and corporate communications; customer service and self-service; supplier and partner collaboration; employee learning and human capital management (HCM); and general knowledge sharing.
Call center reps are finding that wikis, as dynamic self-structuring documents, offer a more updated, cohesive knowledge base from which to address customer problems.
The article talks about uses of blogs and wikis in other companies including Amazon. In addition to knowledge management internal to organizations, they are increasingly being used for customer relationship management (CRM) applications as well.