Honestly, I think whatever future there is in eBooks will be from e-ink devices, not smartphones, iPhones, etc.
Not quite there yet, but they're getting more interesting. There's still something a bit off about the Sony Reader, but I'm curious about the upcoming Bookeen Cybook, for example:
http://www.bookeen.com/ebook/ebook-reading-device.aspx
But it's the e-ink displays that I think really make the difference - I love gadgets, I've loved my Newton, my PDA's, my Treo, and my future iPhone - but I don't like reading lots of text on them.
But I can see myself reading eBooks on e-ink displays.
Again, not quite there yet - the Sony Reader, for example, seems like it has more "dark grey text" against a "light gray background".
I think when e-ink displays get to the point where it is really indistinguishable from what a printed page looks like, that will be it.
Supposedly this Bookeen Cybook does have a better contrast ratio, so I'm interested in seeing that.
Of course, I'd love to see Apple get into making some sort of e-ink device as well.