Ken's presentation "A Canary in a Coal Mine" at Agile2006 conference is available via InfoQ. Ken talks about quality and the danger of Scrum teams droping quality issues to get higher velocity and to be sure to hit the date. He calls this a re-definition of "done", or "somewhat done". We have manifested an increasing technical debt in our iterative work. So in the last project we were putting more focus to acceptance testing inside each sprint and introduced something we called "cross-testing". This means that other pair needed to test the feature implemented by other pair in order to claim feature "done". Embedded firmware systems need a lot of manual acceptance testing (at least our current practice) and it is easy to get slobby testing your own work over and over again.
Was the technical debt there because of Scrum? Well, no - it was made visible by Scrum and the team was able to decide to do something about it early enough.
Ken's another speech about Scrum is available at Google Video. (You will find out that Scrum works with idiots as well)
I posted about Jeff Sutherland's Scrum speech earlier. It is also available via InfoQ.