Rip Remix Case study
Here's an somewhat related Creative Commons case study from on the Canadian mash up documentary Rip: a remix manifesto: http://wiki.creativecommons.org/Case_Studies/RIP:_A_Remix_Manifesto
I also thought this was an interesting article about mash-ups under the current law: http://www.iposgoode.ca/2009/08/a-stroke-of-genius-or-copyright-infringement-mashups-copyright-and-moral-rights-in-canada/
Here's the link to the full 27page article summarized in the link above: http://www.law.ed.ac.uk/ahrc/SCRIPT-ed/vol6-3/reynolds.pdf