This isn't as "obvious" as you think.<p>First, you quoted the human-readable summary of the license, <i>not</i> the license itself.  The CC-BY-NC 3.0 license actually says,<p><i>"You may not exercise any of the rights granted to You in Section 3 above in any manner that is primarily intended for or directed toward commercial advantage or private monetary compensation."</i><p>Note the word <i>primarily</i> - so if the use is only incidentally or secondarily commercial in nature, it may still be compatible with the "non-commercial" clauses.  There are more details in the legalese of the license, but nevertheless this is a very vague and somewhat controversial license - so much that the Creative Commons organization did a survey of community members and published a lengthy report on the different ways of interpreting it:<p><a href="http://creativecommons.org/weblog/entry/17127" rel="nofollow">http://creativecommons.org/weblog/entry/17127</a><p>One question is: Do commercial businesses ever engage in non-commercial activities?  Is Hacker News a non-commercial community site that happens to be operated by Y Combinator, or is it <i>"primarily directed toward commercial advantage"</i> merely by virtue of its affiliation?