Identifying learning in organisations

One important question that I shall be focusing upon in my research concerns the complex subject of how to identify or recognise learning that may occur within an organisation. The debate as to who learns in an organisation (i.e. individuals, groups, the organisation itself) and via what means further complicates this subject of study. I feel that it is relevant to address the issue of how do we know that learning has occurred in an organisation? If organisations themselves can learn then how could we go about identifying evidence of such learning? Should these thoughts be addressed or discussed further in the academic literature prior to considering how to measure learning in organisations?