From ASocialHistoryOfTheMedia (page 8)

Another central concept in the pioneering Innis theory was the idea that each medium of communication tended to create a dangerous monopoly of knowledge. Before (HarroldInnis) decided to become an economist, he thought seriously about becoming a Baptist minister. The economist's interest in competition, in this case competition between media, was linked to the radical Protestant's critique of priestcraft. Thus he argued that the intellectual monopoly of medaeval monks, based on parchment, was undermined by paper and print, just as the 'monopoly power over writing' exercised by Egyptian priests in the age of hieroglyphs had been subverted by the Greeks and their alphabet.

CoryDoctorow's discussion on DigitalRightsManagement has some interesting discussion of changes in media :

My suspicion is that BlogoSphere vs. BigMedia is the same issue as Protestant printing vs. the CatholicChurch. WorseIsBetter printing didn't come with the authority of the pope, but gave more people access. In the same way, blogs don't come with the authority of the brand or the fact-checkers, but give more people access.