Clay Christensen is known for introducing the idea of "disruptive technology" to business. Disruptive technologies are typically products that disrupt established markets by providing fewer bells and whistles than existing products but do so at a lower cost. An example of this is flash memory (more info here:
http://en.wikipedia.org/wiki/Disruptive_technology ).
Disrupting Class (the book and the blog) applies the concepts of "disruption" to education. Christensen and co-authors Michael Horn and Curtis Johnson, provide a vision and strategy for how technology can personalize education for the needs of each student, and perhaps most importantly, how disruptive innovation can overcome the many obstacles that have heretofore prevented reforms in the US education system.
Administrators, teachers, parents, and policy makers would do well to read Disrupting Class. The authors approach education with the perspective of an outsider - business person, technologist, entrepreneur - but the knowledge and thoughtfulness of an insider. Instead of offering didactic or hubristic "fixes" for education, the book provides a framework for thinking about education that is fresh and practical.
Note: the blog is quite good as well - interesting articles on how technology is being used in the classroom, like this post on adaptive learning software that optimizes the way each student learns, while keeping them in the same classroom:
http://disruptingclass.mhprofessional.com/apps/ab/2008/06/03/lilla-g-frederick-pilot-middle-school/