Unlike the iPod, which hooked serious music buyers in addition to a raft of casual listeners, e-book reader adoption will be limited to heavy readers only—at least until prices come down,” analyst Dmitriy Molchanov Molchanov says. “But we see the average price of e-book readers declining by roughly 15 percent per year for the next five years, resulting in 55 percent increase in adoption rate year over year.”

In fact, by 2013:

° U.S. e-book reader sales will reach 19.2 million, a CAGR [compound annual growth rate] of 34 percent, with six million e-book readers sold in 2010 alone.

° The U.S. installed base of e-book readers will hit over 36 million, up from an installed base of nine million by 2011.

° Half of all consumers who indicate interest in buying an e-book reader will have bought one already, so device makers should act quickly.

E-book readers are the leaders of what Yankee Group calls “Anywhere Devices,” a new class of connected products. The research group "expects a host of consumer Anywhere Devices to follow in their wake."

Actually, with the iPad, I think Apple would say they're already here.