Though v1.010 was promised to be the last release, I'm resuming work on the fonts, so here is a new beta of XITS fonts, featuring mainly support for right-to-left math which have been the main motivate behind the project, though never made it to any of the released versions (only supported by LuaTeX for now, more on that later).
Just released a new version of XITS fonts for scientific and mathematical typesetting, no much change from previous beta; fixing an issue (inherited from upstream) that breaks breaks printing with Ghostscript, and fine tuning of two math parameters.
I just uploaded the seventh beta of XITS scientific fonts (don't let the beta label mislead you ;) it is quite functional).
I was trying to change the math font used in plain TeX (as opposed to LaTeX or ConTeXt), but I didn't seem to find it documented any where, apparently it is so obvious for TeXperts to be even documented. Anyway, I figured it out and I'm documenting it here so I don't have to search it again.
Set font families 0-3 to the new font, as follows:
0: math text ("sin", "cos", numbers, etc.)
1: math italic ("x", "y", "z", etc. don't have to be italic at all e.g. Euler)
2: math symbols
3: math extensions
\textfont: normal size font
\scriptfont: font for sub/super script