Nick,
This "shared thinking" is such an interesting area. I remember some earlier work by Jim Hewitt from University of Toronto that really caught my attention. He referred to the problem of "group coherence" which essentially described the difficulties of making learning/process visible in project-based learning. This was over 12 years so there was little available in terms of solutions!
I followed your http://sharedthinking.info link but got to a 123-reg.co.uk hosting page. Is there a another way to get to the site? Can't wait to find out more about your project!