In looking back at 2009, the most significant change in the print industry came from its digital component. While the greatest volume of readership and revenue still flow through the printed product, the digital tail is clearly wagging this dog.

The growth of the internet and the decline of print readership have driven publishers to create digital editions. Readers followed, but sufficient ad revenue did not. In the end, 2009 will stand out as the year that these pressures began to drive change.

It’s become clear that the free content model is not sustainable. Print publishers are hoping to evolve their digital offerings to provide two revenue streams: ad revenue and paid access by readers. However, consumers have been spoiled by nearly limitless free content, so while pay walls may go up in 2010 they may also be taken down.

Most likely, the revenue opportunity will lie with digital devices on which consumers already happily pay for content. New paid electronic editions of GQ and Esquire are already being sold on iPhones. News Corp. recently announced a deal to offer subscriptions to the Wall Street Journal and the New York Post through Sony’s e-reader (the WSJ is also available on Kindle). If successful, these ventures will certainly drive additional offerings in the print industry’s shift from print.