has anyone thought of just having a bunch of cloud servers with LaTeX built there, and then writing a front-end which uploads your docs, compiles them and downloads the resulting PDF? with fast enough servers and good enough data speeds, this might even rival the estimated 10 seconds for a fully ported LaTeX app.

I'm assuming it's been ruled out for other reasons though.

EDIT: this would also make it trivial to use it on android/blackberry, without any extra effort. apparently, also, http://www.scribtex.com/