Here's something of a future shock for you: a couple of months back I signed up to a free online service called NovelRank.com that purports to provide a reasonably accurate estimate of how many copies of a particular title you sell through Amazon on a daily, weekly and monthly basis. This isn't the kind of information Amazon are actually inclined to give away - they still haven't to my knowledge yet given a figure, for instance, on just how many Kindles they've actually sold, for instance - so by means of some comparative algorithm (one assumes) the aforementioned website provides a best-guess figure.
What's interesting about this is that I just checked the sales of the Nova War paperback on that site and assuming it's in the least bit accurate, Nova War has sold approximately three times as many ebook copies in the UK as it has in paperback. Three times. If you listen to most technology/publishing pundits, they'll tell you that ebook sales are already accounting for 10% of overall sales, but assuming NovelRank.com's guesstimate is anywhere near accurate, I'm shifted pretty far along the bell curve and away from the average author.
The effect gets even more pronounced when I look at the sales of Stealing Light in paperback and ebook format over at Amazon.com (the aforementioned sales for Nova War were lifted, by contrast, from Amazon.co.uk). Over there, where the paperback of Stealing Light is relatively expensive and/or hard to get hold of, the ebook version is - by electronic guesstimate - selling six times as many copies.
There are two reasons I can see for this: one - the people who buy my books tend to be drawn, I suspect, from relatively technical backgrounds, or are at the very last early and enthusiastic adopters of new technology - like, say, Ipads and Kindles. This is one reason there was a fairly strong early bias towards sf and fantasy in the first online ebook retailers like Fictionwise. Secondly, and perhaps just as importantly, the ebook versions are a good bit cheaper: $10.79 for the paperback of Stealing Light - but only $6.89 for the ebook over at Amazon.com. Back on Amazon.co.uk, the paperback of Nova War goes for only slightly more than the ebook version, but the price difference is, I suspect, significant enough on a psychological level.
So there you go. Judging by my own rough estimates, the ebook revolution is most certainly here.