Hello, Karl :-)
texexec is just a runner for context (taking care of process management and index sortign and a few more things) and in that sense not related to luatex
By the way, how stable is mtxrun nowadays? Can it be used to completely replace texexec yet? Back to Joel's question, I don't know if my experience in compiling LuaTeX on Solaris can be of any help, but I wish to say it was amazingly straightforward ... of course there were minor issues, but all of them could be set aside with enough patience. Actually the worst problems were caused by the build system (autoconf ...), not the C code itself (I wrote down every change I had to make in my notebooks, but I doubt the exact list be of any interest); many other programs don't build as nicely on Solaris 9, so to me this is a hint that LuaTeX is programmed in a remarkably portable way :-) Probably the most serious problem was caused by Solaris' annoying /bin/sh, and---oh, yes!---/usr/bin/grep doesn't know about a '-q' switch (which is called by the pdfTeX-inherited build.sh at the top of the build tree), so instead of not being quiet it protested loudly, and the script exited. But really, nothing serious, it's only a matter of time to adapt the scripts. Of course I don't claim this is of any interest for Plan 9; I don't know how "far" it is from other Unices. But LuaTeX on Plan 9! The future's TeX running on the future's Unix :-) Next we have to port it to Hurd ;-) Arthur