The report “The Transition to Computer-Based Assessment – New Approaches to Skills Assessment and Implications for Large-scale Testing” has been published. The volume, which is based on a set of workshops that was held in Iceland in September 2008, was edited Julius Björnsson and Fritz Scheuerman. I think it gives a very broad and comprehensive overview of the current state of, and issues around, computer based assessment.
I would especially recommend The article on “CAT as a pedagogic tool” by Jakob Wandall, and “Issues in Computerized Ability Measurement: Getting out of the Jingle and Jangle Jungle” by Oliver Wilhelm.

