We've been writing a lot about eReader devices, but let's focus on the content for a moment. Why? Because selling a lifetime of eBook content to consumers is the end game of many companies in this space, especially Amazon and Barnes & Noble. They sky's the limit here. Consumers don't own digital libraries of books, as they did with music: When mp3 players came out, most consumers owned CDs that could be easily burned to a computer and downloaded to a device. Not so with books.

And the market for digital books, while catalyzed by the existence of dedicated eReader devices, will extend across multiple devices including desktops, laptops, mobile phones, netbooks, tablets, MIDs, portable gaming devices, and devices that haven't been invented yet. As we discuss in a new Forrester report, Forrester's data (based on a mail survey of 4,711 US consumers conducted in Q3 2009) shows that 3% of US consumers read eBooks on their desktop computers today; 2% read on laptops; and fewer than 1% read on dedicated eReaders, mobile phones, or netbooks, respectively. When it comes to future demand, 19% of US consumers say they're interested in reading eBooks on their desktop PCs, 14% say they're interested in reading on eReaders, 11% voice interest in reading on netbooks, and 5% say they're interested in reading on their mobile phones. What this means: Consumers are reading books digitally on multiple devices, and they will continue to do so.

The potential for selling content that's never been consumed digitally before is huge. We project conservatively that in 2010, eBook content sales will top $500 million. This is still small compared to the overall book market, but it's growing quickly--quickly enough to make companies like Barnes & Noble stake their future on the eBook bet. When B&N launched the Nook at the aggressive price of $259--a full $140 cheaper than the other two eReaders with touch navigation and wireless, the Sony Daily Edition and the iREX DR800--they drew attention to their long-term strategy: to profit not so much off device sales as off of eBook content sales. Not only will it be a stretch to make money off of device sales at that price, but B&N has also incurred unexpected costs as they have had to speed up their production schedule to meet holiday demand. They've calculated that these short-term losses are worth it to win over as many lifetime eBook consumers as they can, starting now.

To understand more about which companies are best position to "win" in the Battle For The eBook Consumer, our new report (available in full to Forrester clients) looks at the consumer followings of six companies: Amazon, Apple, B&N, Sony, Target, and Wal-Mart. We chose these companies because they were either already market leaders in the eReader space (Amazon, Sony), major print booksellers (B&N, Target, Wal-Mart), or possible future entrants to eBook eCommerce (Apple). To highlight a few findings from the report:

• Wal-Mart and Target are underplaying their hands. Of the 68 million US consumers interested in reading eBooks on any device, more shop at Wal-Mart and Target than at Amazon or B&N. Of the 30 million US consumers interested in reading eBooks on eReaders, 61% have shopped at Wal-Mart in the past 30 days and 55% have shopped at Target, while 38% shopped at Amazon and 27% shopped at B&N.
• Barnes & Noble has to double-down to beat Amazon. Among the general US population, B&N has nearly the same reach as Amazon: 16% of US consumers report shopping at a B&N store or Web site in the past 30 days, and 17% say the same about shopping at Amazon. But among consumers who are interested in reading eBooks on eReaders, 40% more are Amazon shoppers than are B&N shoppers.
• Sony could compete against an “Apple tablet” wildcard. Consumers interested in reading eBooks on eReaders are three times as likely to be Sony consumers as Apple consumers (24% versus 8%); the numbers are similar for consumers interested in reading eBooks on netbook computers. Among consumers interested in reading eBooks on mobile phones, the gap narrows, but Sony is still the more commonly used brand for this group: 12% are Apple consumers, and 24% are Sony consumers.   

The bottom line? The battle for the eBook consumer is still anybody's game, and we're still in early innings.