After all the reports on the increase in e-reader sales over the holidays, no one should be surprised that February was a banner month for e-books. Indeed, the Association of American Publishers (AAP) is reporting that ebook sales for this February increased 202 % over last February. What’s more, according to the AAP’s report, ebook sales even beat sales for all categories of trade publishing, including adult hardcover, paperback, and mass market, as well as children’s hardcover and paperback.

While we all knew the first few months of 2011 might look like this on the ebook side, I think a lot of people were surprised by just how drastically this has effected sales for physical books. For instance, Thursday brought us the depressing news (via GalleyCat) that sales for all the same categories in print books for trade publishing was down a whopping 34%.

So, print sales are down, ebook sales are up. While it’s possible the dramatic shift in sales toward ebooks is a short-term result of the Christmas ereader binge and will balance out a bit as the year goes on, no one doubts that the future is bright for ebooks. It’s probably too early for print books’ obituary, but it’s probably not too early to start getting used to the idea that the future of print books rests in the book as a special object, something you might want to get an author to sign or the like.

But according to this story by Stephanie Rosenbloom in the New York Times last week, even that function of printed books may be looking at their expiration date. As Rosenbloom notes, the shift toward ebooks is spurring innovation for signed ebooks. And in May, author and inventor T.J. Waters plans to introduce Autography, a new way that authors can sign ebooks:

Here’s how an Autography eBook “signing” will work: a reader poses with the author for a photograph, which can be taken with an iPad camera or an external camera. The image immediately appears on the author’s iPad (if it’s shot with an external camera, it’s sent to the iPad via Bluetooth). Then the author uses a stylus to scrawl a digital message below the photo. When finished, the author taps a button on the iPad that sends the fan an e-mail with a link to the image, which can then be downloaded into the eBook.

The idea would be that this signed image could then be added to the ebook version for whatever devise you’re reading on. So the next time you reboot your Kindle, iPad, Sony eReader, whatever, this “signature” would be an indelible addition to the ebook version.

So if projections are right and half of all books sold by 2015 are ebooks, it would seem that this sort of innovation is inevitable. But I’m curious, what do you think? Is a signed ebook a sufficient substitute?