I've changed this to

    PythonTeX is compatible with all standard LaTeX engines (executable binaries):  
    pdfTeX, XeTeX, and LuaTeX.

There's actually a distinction between the engines and LaTeX.  The engines are the executable binaries, while LaTeX is a format (there are some [additional technicalities](http://tex.stackexchange.com/questions/63994/is-pdflatex-an-engine-or-a-format) that are usually negligible).  I don't want to get into too much detail in the paper, but do want to mention the engines since many people who need non-ASCII fonts use XeTeX and LuaTeX.

I also added a reference to TeX Live and MiKTeX:

    It has been tested with TeX Live [TL] and MiKTeX [MIK], and should work with 
    other distributions.

This is a little broader than what's in the manual, because the next release (out in a few days) removes the requirement for a library that is only in TeX Live and MiKTeX.