Offtopic for the linked article, but the original O'Reilly article says that digital sales will take over physical book sales sooner than people thought.

I think that's true, judging by my own purchase behavior. I haven't bought any O'Reilly digital books yet, but I have bought a few from Pragmatic.

I now prefer buying technical books in a digital format to overcome the high shipping charges(international customer). And although I can pirate most books, I don't. As long as they provide me with an easy way to give them my money and very few restrictions on how or where I can read the content that I bought, I'll be happy to fork over my hard earned dollars. Music downloads on the other hand, don't provide that and so....

What remains is the feeling you get when you grab a physical book and a cup of tea to enjoy on your couch. You get used to reading on your ebook reader and your phone, but it won't be the same. Things are getting better with different reader designs and I think newer generations will find this less of a problem.