I noticed that there's an update for MaemoTeX available. I wonder if a port of LyX (http://www.lyx.org/) would be feasible now?

The reason: I'm beginning to think that a WYSIWYG word processor is not the smartest thing to use on a device with a small screen.

LyX renders text to fit the medium it's being displayed on: so your document will look different on screen than on paper, but that's okay really, because LyX is a typesetter, not a wordprocessor: it will do almost all of the formatting for the user. It's also quite good at outputting files that can be printed directly on other systems, so it circumvents the Nump's problem of not having a printing engine.

LyX does depend heavily on TeX and its assisting programs, so the big question is whether MeamoTeX has everything LyX needs.