As I see it, e-publishing is approaching a point when the three primary forces of the long tail of publishing (democratized production, democratized distribution, and the connection of supply and demand) will converge.(1) This convergence represents a dramatic change in the way mankind will interact with the written word.
Democratization of Production
Prior to the spread of personal computers and the Internet, the only way to write a "book" was using a typewriter. An author or journalist would type their content onto blank sheets of paper and submit their finished content to a publisher or editor. With the advent of personal computers and the Internet, writing tools became increasingly more easier to obtain, cost less, and were more powerful.
Recently, writing tools have even made the jump from personal computers to mobile handsets, where in Japan, half of the top ten selling works of fiction in the first six months of 2007 were composed on mobile phones. Combined, this means that all aspects of the process of writing "books" are becoming more available and in the hands of more producers; a trend which shows little signs of slowing down.
Democratization of Distribution
As more "books" emerge, the Internet makes them almost instantly available to more than 1 billion people. The immensity and ease of use of the Internet also makes the economics of reaching one individual reader the same as reaching the entire Internet user base. Up until recently, that base was confined to personal computers.
Now, however, the Internet is quickly available from a wide variety of cellular telephony handsets. By connecting wireless 3G and 4G networks to the Internet, the number of potential readers for Internet-based "books" more than doubled. With the addition of multipurpose handsets and single-purpose e-readers, the cost of distributing "books" has never been lower.
This also, is another trend that show little signs of slowing down. As many developing nations leapfrog past the wired stage of telecommunications infrastructure directly to 3G networks. This means that the majority of the population of the world, that previously had little access to the written word, will suddenly have the world's largest repository of words at their fingertips.
Connecting Supply and Demand
As tools and distribution converge, what the world will find is a broad array of tools to help them find the "books" they're looking for. While Google is intent on indexing the world's content, Facebook and Twitter are busy building large communities intent on reducing the time and effort between an expressed need and a recommendation.
Of course, many companies are busy building their own stores capable of simplifying the search for content for their own user base (whether they be based on services or devices). Together, these efforts all reduce the "search costs" of finding a "book." Not to sound too redundant, the trend of reducing the "search costs" doesn't show any signs of slowing either.
With all of these forces continuing to cost less and less, the conclusion is clear. In the near future, more people will have access to more "books" than ever before in the history of mankind. This is future of e-publishing.
(1) Anderson, C. (2006). The Long Tail (2nd ed.)(pp.52-57). Hyperion, New York.