After traveling a long, tortuous road, the much-anticipated e-book revolution has finally arrived. So where is the revolution in the "e-textbook" market? According to the National Association of College Stores (NACS), digital books currently account for less than 3 percent of textbook sales. NACS expects that percentage to reach 10 to 15 percent by 2012, while researchers at Simba Information predict that e-textbooks will account for more than 11 percent of textbook sales by 2013. But even this relatively swift growth rate represents a trickle compared to the flood of e-book sales on Amazon. That preference has shown up starkly in some recent surveys. Three-quarters of the students queried by both NACS and the Student Public Interest Research Groups said they would rather use a paperbased textbook than its digital cousin. Matt MacInnis, co-founder and CEO of e-book publishing startup Inkling, sees these responses as an unsurprising reaction to the current state of e-textbook publishing. "All it means is that everything those students have seen up to this point has been junk," MacInnis says. In all the debate about how today's technology can be used to reinvent the textbook, it is easy to overlook something as straightforward as cost. According to Eric Frank, co-founder of Flat World Knowledge, it is one of the primary factors driving the e-textbook market today. Barkan believes that the high price of paper textbooks will ultimately drive students and teachers to embrace less expensive e-textbooks. But he expects the transition to take a while--as long as a decade--as publishers sort out the best way to deliver academic content. (Contains 9 online resources.)