Charlie Stross has posted an interesing q&a about e-books on his blog.
For some background, Stross recently released a novel entitled Accelerando. I've seen good reviews of it in small SF publications as well as more mainstream mags like Entertainment Weekly. In an interesting move, Stross also offers a free e-book version of the novel. He argues that releasing a free version has made his initial sales much higher than for his previous novels, although part of that has to come from an increase in the people reading him in general (his novel Singularity Sky was on many best of 2004 lists). The q&a covers why he did this, and why he thinks it's helped the sales of the book.
If he's right, it could be a whole new approach to PR, particularly for mid-list authors looking for new ways to promote themselves. If he's wrong...then it's just business as usual.