Creative Commons noncommercial licenses include a definition of commercial use, which precludes use of rights granted for commercial purposes:Defining Noncommercial report published
... in any manner that is primarily intended for or directed toward commercial advantage or private monetary compensation.
The majority of respondents (87% of creators, 85% of users) replied that the definition was "essentially the same as" (43% of creators, 42% of users) or "different from but still compatible with" (44% of creators, 43% of users) theirs. Only 7% of creators and 11% of users replied that the term was "different from and incompatible with" their definition; 6% or creators and 4% of users replied "don't know/not sure." 74% and 77% of creators and users respectively think others share their definition and only 13% of creators and 11% of users wanted to change their definition after completing the questionnaire.
On a scale of 1-100 where 1 is "definitely noncommercial" and 100 is "definitely commercial" creators and users (84.6 and 82.6, respectively) both rate uses in connection with online advertising generally as "commercial." However, more specific use cases revealed that many interpretations are fact-specific. For example, creators and users gave the specific use case "not-for-profit organization uses work on its site, organization makes enough money from ads to cover hosting costs" ratings of 59.2 and 71.7, respectively.
I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.