Dude this is awesome! I've had success with sfontmaker (and the gimp script) but I don't like the gradient (this can be disabled) and outlines, I love your script! The kerning support in this script is much better than sfontmaker.
SFont now lives in bitbucket, I have a friendly fork that Karl sometimes pulls from. I dumped your script into my repo and then tweaked it a bit.
My repo is at https://bitbucket.org/clach04/sfont/src/
(python stuff is in the contrib directory, there is a C code generator in there which is nice to making a default font in case the image on disk is missing).
The version there has the Unicode functionality as a parameter, by default it does NOT generate Unicode image fonts.