This had to happen sometime, but I’m surprised it was so soon.

Amazon Says E-Books Now Top Hardcover Sales – NYTimes.com

Monday was a day for the history books — if those will even exist in the future.

Amazon.com, one of the nation’s largest booksellers, announced Monday that for the last three months, sales of books for its e-reader, the Kindle, outnumbered sales of hardcover books.

In that time, Amazon said, it sold 143 Kindle books for every 100 hardcover books, including hardcovers for which there is no Kindle edition.

The pace of change is quickening, too, Amazon said. In the last four weeks sales rose to 180 digital books for every 100 hardcover copies. Amazon has 630,000 Kindle books, a small fraction of the millions of books sold on the site.

On the technology front, this is a red letter day for mobile networks and gadgets, a dark one for logging, paper making, trucking, and printing and pretty much neutral for typesetters and copy editors. It’s going to be interesting to see whether the shift to e-books brings about an increase in literacy.

It’s not hard to imagine new forms of literature with embedded multimedia and ads around long-form manuscripts, and it will certainly become easier to measure patterns of reading behavior than it ever has been. If we find out that readers re-read text about cats, more books will feature cats, etc.