Although my response to the poll was "more than half", it's almost 100% except for graphic novels & manga & some tech manuals, but the issue is availability, not preference. I recently upgraded from an iPaq 2210 to the HTC Advantage & as much as I enjoy all the extra features, the only reason to cough up all that $$$ was because of that gorgeous huge VGA screen. My old eyes are very grateful.
On software, I use uBook almost exclusively. Whatever books I get that are DRM'd get promptly zapped down to html or rtf, so I'm still buying them on lit format since it's the only one I know how to zap.

ops: I'll give you a call, Steve.
For hardware, I welcome things like the Kindle because the future will certainly be digitized. No, I don't intend to buy one, it's too big, too expensive, too plain (feature-wise), etc, but anything that can hook people into ebooks is a step in the right direction. As has been discussed here already, personal preferences go from the tiny to the very big, there's room for all. I eagerly await the waterproof floating screen that can follow me to the bath. :lol:
In any case I expect for everyone the #1 reason for ebooks is the size/space convenience. Lots of choices without carrying around pounds of printed stuff. Oh, and God knows I could recover oodles of extra space in my tiny apartment if I could digitize the hundreds of books filling every shelf, box & corner. And yes, I've bookmarked Mark's guide, but I want a way to scan without destroying the books, even if it's slow & painstaking.
Publishers may be afraid of people copying their stuff for free, but those of us that bought books before still buy them today & will still buy them tomorrow. I certainly would buy more ebooks if the availability & prices were better since I wouldn't have to worry about where the hell I'm going to put them.
Rosie