Read Glenn Reynolds at www.techcentralstation.com. His bottom line: We have enough blogs about wars and campaigns. Cover local politics, local bands, area restaurants. Use video if you can. In other words, think global, blog local, if you wish to change the world.
The economist in me: Can you have overcrowding in one blogging area? Say you have two roads to a destination, and drivers can observe how crowded each road is. Under some conditions drivers will allocate themselves efficiently across the two roads (average returns will equalize, marginal returns may not). So if the private returns to blogging in one area fall through crowding, some rough mechanisms operate to induce bloggers to leave that area. You might blog in a new area to attract a bigger audience, for instance. Alternatively, Glenn may be saying that local blogging has a higher social than private return, relative to blogging the national scene.
And if they had asked me? For economics, we are still at the margin where new blogs enhance each others’ value, rather than lowering it.