Some great work is happening on evaluating the benefits of electronic assessment in HE externally. A project team at the University of Huddersfield is currently evaluating the impact of e-assessment and feedback on student satisfaction, retention, progression and attainment as well as on institutional efficiency and are sharing recommendations for achieving high quality assessment processes, staff development, student support, sustainability, scalability and curriculum development.
Please check out their blog for information on the project and work relating to e-assessment generally. http://library.hud.ac.uk/blogs/projects/ebeam/.
There is a good post containing an overview of a recent Turnitin user group meeting and future enhancements of the Turnitin product that are coming in the, relatively, near future. http://library.hud.ac.uk/blogs/projects/ebeam/2012/07/16/iparadigms-focus-group/