Yes, I have thought about making it into an open-source project, like Pat Morin did with his Open Data Structures textbook, or Boaz Barak with his Modern Complexity Theory textbook. (Both highly recommended, BTW.)

But I'm hesitant to release the LaTeX source files in their current (rather grungy) form. Too much of a control freak, I guess. Maybe for the next edition.

Also, the figures are all in a closed file format (OmniGraffle). In principle, I could convert everything to an open-source format like svg, but (0) converting everything would be hell, (1) LaTeX doesn't understand svg files directly, (2) in principle, I can connect latex to inkscape to convert svg to pdf, but the translation is always imprfect, (3) using Inkscape makes me want to tear my hair out, and (4) I'm a control freak.

And don't even talk to me about tikz.