QT - even just MinGW and msvs - takes a long time to install and takes up a lot of space (I'm waiting for it to install now and it's been installing for like an hour), so unless you have time and find comprehensive tutorials on how to compile .pro files and put everything into a neat little .exe, I doubt QTAU will take off beyond it's linux roots and be accessible to windows users. I'm tech savvy, but I'm not a linux enthusiast beyond the basics, nor am I a programmer who finds the idea of compiling things titillating. I can...
try to compile it just to see if it works and if I can make an exe out of it, but I won't make any promises.
@Tomato Hentai, thanks for pointing it out and all, but I doubt the average user is going to have this kind of patience to install 3Gbs worth of QT just to get a single program to - possibly - work as an alternative to the UTAU interface.
EDIT: I'm now down to 32Gbs of space on my hdd and after looking through all the folders, there is no makefile for QTAU. Everything is still in a .pro state and... I have no idea what I'm looking at when I open them. I understand not wanting to reinvent the wheel, but people need something easy and intuitive where they can just open it and use it without a lot of mucking around in programming tools.