I’m the supervisor of Michela Ferron, PhD student at the Center for Mind/Brain Sciences of the University of Trento and working with me in the SoNet group of the Bruno Kessler Foundation.
Her project is on formation of collective memories in Wikipedia and she just put up an interesting blog I suggest you to check. You find it at http://empiricalmemories.wordpress.com.
Below a video showing some comments posted during the fifth anniversary of September 11 attacks and during the first anniversary of the Virginia Tech massacre (occurred on 16 April 2007) on the related Wikipedia talk pages. But on the blog there is much more.