Chet Marchwinski of LEI conducted a short interview with Art Smalley regarding problem solving and improvement. The video was just posted on-line by LEI at the following link:

http://www.lean.org/LeanPost/Posting.cfm?LeanPostId=628

The book on the 4 Types of Problems is due to be published by LEI later this year. I will announce any updates when we hear of a release date