In this article on his blog, Om Malik asked the question in the title. As I commented there, this reminds me of the discussion/debate that took place in the 1980s around the causality of telephone penetration and economic activity. The net result of this debate was fairly inconclusive.
Is this debate at all germane to Om Malik's questions? Does it matter that we discussed telephone technology in the 1980s and broadband technology today? Does it matter that the previous debate was on national development, while Om Malik is interested in transational effects?