I need to do this post to make everything clear.
Most of this has been covered in recent posts, but this is the short all-in-one summary.
1) eInk = monochrome non-backlit display suited to viewing lightly tarted-up text files.
2) eBook = lightly tarted-up text file exemplified by the "industry standard" of --
3) ePub = an alleged "standard" pieced together by a committee without teeth, now a footstool of Adobe.
4) Axis of E = 1 + 2 + 3.
5) Digital book = multi-dimensional interactive book with a rich back-end metadata component that can connect to other digital books. What books need to be.
6) Google Book Search = there is no need to rush into this, it is based on a false understanding of what an "electronic book" is. Google understands the difference, so they want to rush.
People also wonder if I still endorse something like the Sony Reader (I have never endorsed the Kindle). Only conditionally:
1) You do not purchase any "eBooks" for it (because it's likely you will have to repurchase those in digital book format)
2) You use it for library loans
3) You use it for public domain books
4) You use it for free eBooks
5) You use it to view your own material (manuscript, RSS feeds, etc)
I am, in short, now opposed to buying anything called an "eBook," because it's contributing to a "standard" that is doomed to be swept away.
Save your money. Borrow print books from a library.
It will be worth the wait.