Just like the Web 2.0 has transformed the Web and the
way people use the Web, we believe that Web 2.0 has the po-tential to transform research in technology-enhanced learn-ing. We base this claim on two observations: rst, on the
wealth and variety of Web 2.0 services that are available
today, and second, on the low complexity of exploiting the
functionality of the services by APIs, which allows to imple-ment functionality on top of these services