This article inquires whether and to which degree some fundamental traits of the World Wide Web may encourage us to revise traditional conceptions of what constitutes scientific information and knowledge. Turning to arguments for 'open access' in scientific publishing and its derivatives (open content, open archives, etc.), contemporary tendencies in 'social software' and knowledge sharing, the authors project a new look on knowledge, dissociated with linear notions of cumulation, progression, and hierarchy (e.g. of scientific argument), but related to circularity, heterarchy, and evolution. Arguing from a medium theoretical perspective, they illustrate their ideas with developments in library science, current debates in epistemology and theories about information architecture, with a particular focus on 'unsystematic' folksonomies.