This may be important, because our societies have a long tradition in regulating non-profit organizations. There are laws that contain the knowledge of how to protect the various interests, although they differ widely between countries.
The wiki is a special case because at first, no money is involved and the interests are usually not that strong. But surely all this will change when wikis will grow and become important. It's a pity, like losing innocence. It may be inevitable, because we work for making our wikis great. Conversion to an explicit non-profit organization may be the natural next step in the life-cycle of a successful wiki.
On the other hand, any wiki and any OnlineCommunity may be built for profit. Why not? But either the founder makes this clear from the beginning — then he may have problems to find contributors — or he will have to transform the community from non-profit to commercial. Might be interesting to see how this can be done. Does anyone know examples? -- HelmutLeitner
See also [Cornell University's page on non-profit organizations].
To show the importance of non-profit organizations e.g. here in Austria: population 7.5 million and >100.000 non-profit organizations.