gnuplotfortran (and fortranposix), should work on any Unix like system that supports a runtime C library like glibc. User reports from a person using gnuplotfortran on IBM's XL Fortran system indicate that the AIX version of ld has some issues with it. At the time of this writing, I am not aware if that issue has been sorted out.
To summarize what we need :
If you succeeded in porting gnuplotfortran and fortranposix to a new platform and/or compiler, let me know.