Here's an example of vim running on an eink device (http://www.youtube.com/watch?v=FdmX52SCpG0). A lightweight, long battery life eink-coder would be a fantastic thing to have when travelling.
I'm still waiting on my Raspberry Pi (if it ever gets here, I've been waiting 6 months) with the dreams of turning it into a small, Radio Shack-style Vim machine. Building a case with a keyboard, a small display screen, a command line, and a huge battery. When it's connected to the Internet, it would push the changes up, but when it's not it would cache it locally.
Sometimes I like to go camping while I work, for the peace of mind of sitting in nature away from everyone. Really lets me focus. My Thinkpad gets 10 hours of battery life, but that's not always enough. Charging it in my car isn't really congruent with getting away from it all.
I have similar dreams but then a battery powered emacs machine. As a homebrew Raspberry Pi powered device will probably needs more power then a hacked phone running linux I'll opt for the latter. If only such a phone had a vizplex e-ink display! There is a PocketBook which supports a bluetooth keyboard, also a nice option.
A hacked phone might need less power, but it's also smaller, which means a smaller battery. My phone gets 10 hours of battery life in constant use, and my laptop gets 10 hours of battery life in constant use. Obviously the laptop has a much, much larger battery, and sits in a much, much larger footprint. Imagine phone-grade hardware with a laptop-sized battery.
I'm not criticizing your version of the dream. That's the beauty of open technology, everyone can have their own dream and see that it becomes reality with a little bit of work. What I was thinking of would be about netbook sized with the majority of it being battery. Full sized keyboard mounted in, console-sized display, leaving a huge empty space inside. Without having it in my hands to actually judge battery use, all I can do is dream of a 30-hour battery on a black-and-white, unbacklit display powered by a full sized keyboard.
IMHO the eInk people are missing out by not getting their displays in the hands of more hobbyists. There aren't any reasonably priced development kits anywhere, they're nearly as expensive as the end-user devices. A lot of the end-user devices aren't hackable or have other compromises. Correct me if I'm wrong.
Grayscale vim would be good enough for me: http://sstallion.blogspot.com/2010/10/newsprintvim-pleasant-...