OECD has written a report about on-line music distribution. The findings are quite interesting, given the heated debate.

Too many incompatible audio and DRM formats and hardware devices could depress the growth of online music. […] DRMs are essential to new content business models, yet they have often failed to prevent unauthorized uses. Concerns over transparency, privacy, and comparatively restrictive terms of usage rights (e.g., denial of fair use) are also flagged.