The patch as it stands causes _ctypes build failures when using the 10.4u SDK as in the traditional 10.3+ 32-bit-only installer configuration.  Apparently, in ppc-ffi_darwin.c, the skip that the patch removes was because OSCacheControl.h doesn't exist in the 10.4u SDK.  It is in the 10.5 SDK and _ctypes.so builds and tests OK on both PPC and i386 with it.

--- a/Modules/_ctypes/libffi_osx/powerpc/ppc-ffi_darwin.c
+++ b/Modules/_ctypes/libffi_osx/powerpc/ppc-ffi_darwin.c
@@ -37,19 +37,10 @@
 #include <ppc-darwin.h>
 #include <architecture/ppc/mode_independent_asm.h>
 
-#if 0
 #if defined(POWERPC_DARWIN)
 #include <libkern/OSCacheControl.h>	// for sys_icache_invalidate()
 #endif
 
-#else
-
-#pragma weak sys_icache_invalidate
-extern void sys_icache_invalidate(void *start, size_t len);
-
-#endif

./Modules/_ctypes/libffi_osx/powerpc/ppc-ffi_darwin.c:41:67: error: libkern/OSCacheControl.h: No such file or directory