I published "The Cultural Diffusion" on my website in 2004. The Longtail theory was a prominent idea then, that the transition from monolithic, one-way communication systems to granular, interactive systems would create small but profitable niche markets.
From a cultural point of view, a long tail might express itself as a "cultural diffusion"... fringe cultures growing at the expense of the core culture. And this should be measurable by comparing keyword counts (memes) over time - an increasing number of memes but with smaller impact and count, like this:
Let's derive some interesting conclusions. If information grows faster than its consumers, each person knows less and less of the total. All things being equal, shared information (common culture) will shrink because each person possesses less and different information.
With less in common, we can expect an increase in conflicts and miscommunications. I think it's safe to say that's been the case for the past several years.