Like the variety of Web 2.0 applications, theories of learning and instructional models are also primarily content independent. So it is left up to the teacher educator to match learner characteristics, content, pedagogy and technologies. This presentation will concentrate on the use of Web 2.0 technologies in contemporary constructivist and cognitivist learning environments. We will present the characteristics of Web 2.0 tools to support teaching and learning, including low threshold applications, a variety of tools and models, as well as access to tools and knowledge. Finally, we will identify the limitations and challenges that exist with using these tools, such as immature applications, longevity of applications, number of applications, unconsolidated services and security and ethics.