I have been reading Richard Mayer's work on Multimedia Learning. In his introductory chapter Ihe reminds us of central problem with a lot of the work that is going on in regards to blogs, wikis, podcasting and the like. Too many of us (me included) are focused on the technology and not on the learning. Here is the difference that he captures with these two questions:
Technology-centered people ask: How can I use these capabilities in designing multimedia presentations?
Learner-centered people ask: How can we adapt multimedia to enhance human learning?
He asserts that if we focus on web or other technologies we will be disappointed by the outcome just as we have been disappointed by all the previous technologies that were going to revolutionize education-- radio, televsion, etc. See L. Cuban, 1986, Teachers and machines for a more elaborate story about the failures of technology.