Really good point on the SMTs @fourfourfun. I can see that working both ways though (depending on how well the communities functionality separates groups of users).

You could easily imagine SMTs being set up to reward users for putting forward certain views, or for sharing certain posts. Comments boards in mainstream media are already (I believe) swamped by paid-for commentators. Now you have a system which allows you to reward anyone for doing this work, rather than having to hire people specifically.