As an update to my excitable post below announcing the demise of the Longtail, it's worth directing people to Chris Anderson's post which responds robustly to MCPR-PRS's claims.
Rather than being "thoroughly debunked" it seems that a real interpretation of the The Longtail's validity depends on the type and scope of data used, and presumably the methodological approach taken by the researchers.
Now I should have checked my enthusiasm at debunking, especially as I am only too aware of the different results thrown up by different approaches to research. In fact I suggested as much in response to Jed Hallam's comment below!
Sorry to Chris Anderson for being to hasty to snack on an internet scandal :)