I am blogging my PhD in 'Value and Quality Assurence Volunteer Generated Geospatial Information (VGGI)' here:

http://chris-researchblog.blogspot.com/

This is fundermentally how we can judge the relative worth of geospatial data generated by amature users. This has yet to be fully investigated at an academic level, so its all very exciting. Although OSM is not my PhD, OSM is a good case study, so my work may be very relivent here!

enjoy!