We believe that a next step regarding "Web 2.0" is to provide virtual communities related to a particular object (movie, event, ...) so that one can easily find all user-generated content and people related to it.
Still, we must solve the issues of interoperability between social media websites and link people and content not only to simple tags, but to those objects / concepts.
We think that Semantic Web technologies can help to achieve those two goals, and our current efforts in that direction include the SIOC project, a model and food-chain to represent activities of online communities, and MOAT, a process to bridge the gap between tagging and semantic indexing.