Well, I think it shouldn't be that hard to figure out if the iPod is having an impact on book sales. Since Fictionwise happens to both sell books and one of the applications used to read books on the iPhone/iPod Touch, they should be able to tell us how many people who downloaded the software actually bought books.
Actually, in Early August, they did. According to teleread (
http://tinyurl.com/3etkmy), as of August 13th of this year, over 35,000 of the 130,000 iPod users who had downloaded the software had actually bought books (it doesn't say how many of those had bought multiple books). Now that was more than a month ago, and I believe the number of eReader software downloads has increased to something like 300,000... if the number of book buyers has also increased, then that means Fictionwise might have close to 100,000 new customers.