constructivist or contrived?

I keep thinking about the wikibooks and other 2.0 things we're reading about as they are used in the classroom. Here's my question, when instructors use these tools, is their teaching inherently constructivist, due to the participatory/interactive nature of these tools? Or is it true that requiring students to participate in this way for a grade is contrived and doesn't at all employ 2.0 technologies in the way that they were intended for?