Aaron Swartz did some initial research comparing Wikipedia contributors by number of edits and characters, arguing that the core community (who make most of the edits) should matter less than peripheral domain experts (who write more). He is running for the Wikimedia Foundation's board as a proverbial outside the beltway candidate with a populist platform. In his previous essay he noted that the core community was more engaged in the details of technocrats than high minded theories of what Wikipedia means for the world.
However, one Wikimania session attended primarily by these technocrats and a couple of board members was on very similar but deeper research. The core community does the heavy lifting to allow a numerous and diverse body of content contributors. I'd suggest at least part of the core community is aware of this. After all, all those edits amount to interaction with content contributors.
I personally believe how Wikipedians relate to casual contributors over time and scale is a core issue. This is an area for further research to inform policy decisions and administrative practices. Perhaps we could help Aaron get some computing cycles or a research partner to take this further.
In other news, the NY Times has an article on consumer advertising supported wikis.
UPDATE: JP says it better than I did now or before, which is increasingly the case.