The recent addition of the posix_spawn gnulib module raises the possibility of getting this functionality to work on MinGW, since the gnulib module provides portability to MinGW and friends.
The first step is to remove the HAVE_FORK ifdefs where unnecessary in posix.c, since piped_process() does not use fork. This will allow the functions to be exported. Guile's homegrown waitpid in posix-w32.c is apparently not compatible with gnulib's posix_spawn since they use different stores for PIDs and process handles. The gnulib waitpid will need to be imported and Guile's custom waitpid removed. Also, various hardcodings of "/bin/sh" and "/dev/null" will need workarounds. If it could be made to work, it would still not function identically to how it functions on GNU/Linux because of the different shell, but we already accepted such divergence previously when 'system*' used the start_child from Guile's posix-w32.c -Mike Gran
