So let's take a quick look at each.
Yes, as stated in the NY Times article, there probably isn't as much saving over print versions as we all imagine. So consumers need to be realistic. On the other hand, when I can buy a paper copy cheaper than the electronic one, you know things are off. I don't care if you put the price of the printed versions up (well, I do) but e-books must be cheaper than a paper equivalent. So when the hardcover is out, it should be cheaper than that, and when the paperback is released, it needs to drop in price to be cheaper than it. Simple.
So how come, over at Waterstones the hardcover version of Dan Brown's The Lost Symbol is £9.79 and the eBook (as they state it) is £13.58? And that's in a 30% off eBooks offer as well. I'm sure there are some arguments about competition, maybe the publishers don't want people to buy the electronic copy. For electronic sales to kick-off though, that should be at least the same price (you could argue it's immediately available so this offsets the relative extra cost). It's not limited to hardcover/new release books either. Angels and Demons is available for £4.79 in paperback (two different versions) but is £6.54 for the eBook.
Now take into consideration that you can't loan the electronic copy (sometimes you can, but only if allowed and only if your friends have a compatible reader) and you can't sell it on when you're done as you can with a physical copy and electronic copies fall behind again.
So, the price needs to be below the cheapest available paper copy.
Amazon doesn't even list e-books for sale, though the likes of Waterstones, WHSmiths and CoolerBooks do. What you'll find is a relatively tiny range limited to brand new blockbusters and cut-price classics. Typically the female-dominated crime sector doesn't do too bad, but anything else is missing so much you'll easily find gaps. None of the Harry Potter books are available in electronic format by way of an example.
You can't even guarantee all of an author's back catalogue is available. Taking Dan Brown as an example again, three of his five novels are available (The Lost Symbol, Angels & Demons and Deception Point) but not the best selling book of all-time: The Da Vinci Code.
To make matters more interesting, some stores have different versions (not different formats) of the same book. CoolerBooks has three versions of Angels & Demons listed, two at £4.86 and one at £5.56, I've got no idea what the difference is.
Which brings is on to interoperability. Amazon's Kindle uses its own format, CoolerBooks has a whole page dedicated to the formats available. WHSmiths talks about four different formats but Waterstones seems to stick with one. Which one is compatible with which reader? No idea.
MP3 is currently the standard for online shops selling music downloads. Not because it's the best format, far from it, but it works on the widest range of hardware. As has been shown before, proprietary formats don't work and eventually consumers will force a winner. PDF and EPUB seem to be winning the format war, so I expect the Kindle to start supporting it soon and, whether it's the best or not, so we'll eventually end up with a standard.
Whether that works on all the hardware is another matter (because of DRM). As seen in the music industry, the DRM will be subverted soon enough and so they might as well drop it now. That would drop this barrier so at least I can take my eBooks with me and read them on whatever hardware I choose to buy.
Is that it? Is that all that is holding back adoption of e-books? No, the hardware is not there yet either, but it's coming. Wholesale adoption, especially by those who read the most, is probably help up by availability the most. More books need to be available before it becomes viable to switch.
Incidentally, when do we get to drop the hyphen? E-book, eBook, ebook? We'll get there eventually.