Hi Dan. Now I get to it, I see that you are already planning to do what I was going to suggest - getting them to plan a lesson.
Is the audience too disparate to create groups of teachers from the same subjects? It would be great if they could bring along a real topic they are about to teach and then work on how the whiteboards could enhance the teaching and learning for that topic. The key, if we agree with what the DFES study says, is to keep the focus on learning and teaching methodology rather than on technology. Low level use of whiteboards might sound like "how could we use that drag and drop thing here" whereas high level use would sound more like "we should incorporate an opportunity for peer assessment here - could the whiteboard help with that?"