It the nonprofit world, board members do not usually get paid. Members are usually viewed as volunteers with a so-called "sacred" duty to care for the organization and its work. As best as I understand, there are few if any laws that prohibit compensation but the general thinking is that this is part of volunteering and that the driver is mission.
But what happens when the work of being a board member is really hard and demanding (oops, isn't that true for most nonprofit boards?)? Well, the case with the Rauschenberg Foundatiion is certainly one example where the perceived experience as board members has just been too much to handle and now the matter of compensation has become a legal matter.
Generally I believe that if folks who are thrust into or choose to be thrust into trustee service expect compensation, that expectation should be clear from the start and the institution should accept service with this understanding. What I see is a late-in-the-game seeking compensation and I believe this to be a problem, not as much as the idea that compensation is warranted.
Bottom line: prospective board volunteers should know the terms when signing the dotted line BEFORE service. After the fact: YOU ARE TOO LATE! STOP SERVING!
For the story, see the Chronicle of Philanthropy.