Amazon Kindle book sales soar

Online retailer reports sales of its digital e-books has outstripped those of traditional paperbacks.

During its earnings announcement today, Amazon released some tantalizing tidbits that show just how its book business has evolved in the past year. The company still won't discuss hard and fast numbers for actual Kindle devices sold, or books sold for that matter, but that doesn't make the new information any less noteworthy.

Amazon says that, for the first time, it has sold more Kindle e-books than paperback book. Since the start of the year, Amazon has sold 115 Kindle books for every 100 paperbacks. Kindle book sales continue to outpace hardcover sales, as well; during the same time period, three times as many Kindle books were sold as were hardcover books (including sales listings for books that have no Kindle edition).

These are certainly compelling numbers-particularly Kindle sales as compared with hardcover sales, a trend with first began to manifest itself last spring. In July 2010, Amazon announced that in the one month period between June and July, 180 Kindle books were sold for every 100 hardcovers.

While no one doubts that there's a clear shift underway to the digital consumption of e-reading materials, I have to wonder if the dramatic boost can be attributed to the post-holiday time-frame these numbers represent. After all, the Kindle was a popular gift this holiday season; Amazon remains coy with actual numbers, but did divulge that it "sold millions" of its third-generation Kindle reader in the fourth quarter. Armed with that info, one would imagine that all of those new devices had eager new owners anxious to get a digital library started.

None of this is to say that a boost in Kindle says is a temporary phenomenon. Certainly, those devices will continue to foster sales of new book content as time goes on. Plus, Amazon will continue to do well with its cross-device strategy-the latest Kindle app is for Windows Phone 7. And the company already has amassed 810,000 Kindle books, not counting public domain books; at this rate, a million titles can't be far behind.

But it could be premature to determine that Kindle book sales have tripled vis a vis hardcover sales. Before we can tell just how seismic the shift is, and how much faster than expected it's proceeding, let's see how the buying trend evolves across the next several months, which won't include the post-holiday crush.