I just built Ghostscript version 8.64 for Mac OS X 10.3.9, 10.4.11, and 10.5.6. When installing on my 
10.4.11 machines (both PPC and Intel) I get the following error:

gcc  -DHAVE_MKSTEMP -DHAVE_HYPOT   -DHAVE_FONTCONFIG -O2 -Wall -Wstrict-prototypes -
Wundef -Wmissing-declarations -Wmissing-prototypes -Wwrite-strings -Wno-strict-aliasing -
Wdeclaration-after-statement -fno-builtin -fno-common -DHAVE_STDINT_H -
DGX_COLOR_INDEX_TYPE="unsigned long long"  -DUSE_LIBICONV_GNU  -I./obj -I./base  `cups-config 
--image --libs` -DBINDIR='"/usr/local/bin"' -DGS='"gs"' -o bin/pdftoraster cups/pdftoraster.c
cups/pdftoraster.c:62: warning: no previous prototype for 'parseOpts'
cups/pdftoraster.c: In function 'parseOpts':
cups/pdftoraster.c:76: warning: implicit declaration of function 'cupsRasterInterpretPPD'
cups/pdftoraster.c: At top level:
cups/pdftoraster.c:80: warning: no previous prototype for 'parsePDFTOPDFComment'
cups/pdftoraster.c: In function 'main':
cups/pdftoraster.c:114: error: 'cups_array_t' undeclared (first use in this function)
cups/pdftoraster.c:114: error: (Each undeclared identifier is reported only once
cups/pdftoraster.c:114: error: for each function it appears in.)
cups/pdftoraster.c:114: error: 'gs_args' undeclared (first use in this function)
cups/pdftoraster.c:115: warning: ISO C90 forbids mixed declarations and code
cups/pdftoraster.c:178: warning: implicit declaration of function 'cupsArrayNew'
cups/pdftoraster.c:188: warning: implicit declaration of function 'cupsArrayAdd'
cups/pdftoraster.c:422: warning: implicit declaration of function 'cupsArrayCount'
cups/pdftoraster.c:424: warning: implicit declaration of function 'cupsArrayFirst'
cups/pdftoraster.c:425: warning: implicit declaration of function 'cupsArrayNext'
make: *** [bin/pdftoraster] Error 1

It appears that 'cups_array_t' is defined for CUPS 1.2 and above, whereas Mac OS X 10.4.11 use CUPS 
1.1.23. For whatever reason Mac OS X 10.3.9, which uses CUPS 1.1.19 does not have this problem and 
generates no error when installing Ghostscript 8.64. Mac OS X 10.5.6 uses CUPS 1.2.x, so there is no 
problem here anyway.