Creative Commons just released Defining Noncommercial: A Study of How the Online Population Understands 'Noncommercial Use'. (pdf link). Here's a snip from the beginning of the empirical findings section:
The empirical findings suggest that creators and users approach the question of noncommercial use similarly and that overall, online U.S. creators and users are more alike than different in their understanding of noncommercial use. Both creators and users generally consider uses that earn users money or involve online advertising to be commercial, while uses by organizations, by individuals, or for charitable purposes are less commercial but not decidedly noncommercial. Similarly, uses by for-profit companies are typically considered more commercial. Perceptions of the many use cases studied suggest that with the exception of uses that earn users money or involve advertising – at least until specific case scenarios are presented that disrupt those generalized views of commerciality – there is more uncertainty than clarity around whether specific uses of online content are commercial or noncommercial.
Research was conducted by Netpop Research. The raw data has been published under the CC0 license.
Congrats to the CC team and Netpop on publication of this important resource for the on-line community.