With regard to the adoption of Web 2.0 technologies OA journals behave unevenly. The great majority of OA journals (roughly 71%) do not adopt Web 2.0 technologies. Among OA journals using Web 2.0 tools different levels of uptake can be tracked ranging from journals which adopt feeds as a unique Web 2.0 technology to journals belonging toTier Two and Three which clearly show signs of innovation in format and publishing structure. Particularly in OA journals classified in Tier Three distinctions between journals and blogs (i.e. Acta Societatis Martensis , Journal of Music and Meaning) and between journals and portals (i.e. Tate Papers, Sonograma Magazine) are blurred and the boundaries between types and forms of publication become less clearly defined. The size of an OA publisher is not predictive of a high level of adoption of social web technologies: the large OA academic publisher Bentham Open (more than 230 journals) does not implement Web 2.0 technologies while BioMed Central ( 237 journals) implements a full set of different Web 2.0 tools for researchers. Again, Subject category does not predict adoption of Web 2.0 technologies. However some differences can be ascribed instead to qualitative aspects of the research performed by the referring scholarly communities. OA journals in the Arts and Architecture tend to publish more blogs and pay more attention to editorial and multimedia aspects. Due to the rapid evolutions and spread of Web2.0 technologies, further analyses will be necessary in the near future to provide a deeper understanding of the OA publishing systems and adoption of these technologies. In particular, it would be interesting to examine qualitative and quantitative differences in the uptake of Web 2.0 technologies among Toll Access (TA) and OA journals and publishing platforms.