"All for One, and One for All": we discussed the benefits of tight communities--and the disadvantages, such as a loss of privacy, of options, and (sometimes) freedoms.
We can see McKibben's argument as being implicitly utilitarian: that local economies produce more satisfaction and less harm for more people than our current economy. How would someone argue with him on this point? Probably, it would have to be done on the basis of showing that his calculation of the benefits and disadvantages left something out.
One such disadvantage (which we did not discuss) is the possibility that tighter communities are related to higher levels of conflict between different communities--nationalism, racism, and the policing of ingroup/outgroup loyalties.
It's also plausible to see McKibben as relying on an argument from virtue ethics. You might read his argument not as a strict calculation of utility or preferences, but rather as an argument that says that certain qualities make for more virtuous communities and certain communities lend themselves to the flourishing of a certain kind of good character. He thinks our material and economic culture value things, people, and services that are "fast, cheap, and easy." Instead, he thinks we should build cities and economies which are deliberate, valuable, and lasting. This would promote virtues which are currently neglected, such as loyalty, responsibility, creativity, etc.
A question to consider is whether the only way to achieve the postive results that McKibben attributes is to cultivate cohesive communities that are local in geographical terms. Does technology permit us to participate in communities that are tight and supportive but distributed in space? Although McKibben is concerned with the transport of goods and the environmental toll of transportation, our economy is increasingly based in services, and knowledge and communication are no longer bound by space.
Along these lines, last fall I heard a report on NPR that, for a variety of reasons, local banks are much less affected by the banking crisis than the large conglomerates are. You can listen to the story here.
Also, a former student passed along this interesting timed map of WalMart's spread.