I would like to recommend for the 2013 Best Related Non-Fiction Hugo Award category the book As If: Modern Enchantment and the Literary Prehistory of Virtual Reality (Oxford University Press, 2012) by Michael Saler. It's a history of imaginary worlds and how science fiction and fantasy fans transformed them from literary worlds to "virtual worlds" by discussing them in fan clubs, fanzines, letters pages, etc. These worlds were not escapist, Saler shows; readers used them to understand the "real" world, and to come to see it as, in many respects an "imaginary" world itself, open to question and change. There is more information about it here:
http://www.amazon.com/As-If-Enchantment-Literary-PreHistory/dp/0195343174/ref=sr_1_1?ie=UTF8&qid=1355714691&sr=8-1&keywords=saler+as+if