The nature of collaborative learning involves intensive interactions among collaborators, such as articulating knowledge into written, verbal or symbolic forms, authoring articles or posting messages to this community's discussion forum, responding or adding comments to messages or articles posted by others, etc. Knowledge collaborators' capabilities to provide knowledge and the motivation to collaborate in the learning process influence the quantity and quality of the knowledge to flow into the virtual learning community. In this paper, we have developed an ontology enabled annotation and knowledge management to provide semantic web services from three perspectives, personalized annotation, real-time discussion, and semantic content retrieval. Personalized annotation is used to equip the collaborators with Web based authoring tools for commenting, knowledge articulation and exertion by extracting metadata from both the annotated content and the annotation itself, and establishing ontological relation between them. The real-time discussion is used as a bridge to link collaborators and knowledge and motivate collaborators for knowledge sharing by building profiles for collaborators and knowledge (in the forms of content and annotation) during every discussion session, and establishing ontological relation between the collaborators and knowledge for the use of semantic content retrieval. The semantic content retrieval then utilizes the ontological relations constructed from the personalized annotation and real-time discussion for finding more relevant collaborators and knowledge. (Contains 1 table and 6 figures.)