Usually audiobooks are published after print books, but recently Mignon Fogarty, who hosts a popular podcast called Grammar Girl, reversed the process.
She found out that she was going to be on the Oprah Show before her print book would be ready. So she'd have something to promote on the show, she put together a little audio book in record time. The day she was on Oprah, the iTunes home page featured "Grammar Girl's Quick and Dirty Tips to Clean Up Your Writing," an hour-long audiobook that sold for $4.95. By the end of the week, they had knocked "The Secret" off the top spot on the chart.
Jon Stewart's "America" was also released in audio form ahead of the book and the publisher believes that this helped build a buzz for the print edition. According to an article in the International Herald Tribune, there are also an increasing number of audio projects that stand alone. They cite the example of a collection of Jimmy Carter's adult Bible class lectures, and a collection of audio-only Stephen King short stories (read by him).
It's another sign that there's a shake-up going on in publishing, and alert writers will be thinking of how they can turn these developments to their advantage.