I finally have a stable system to use to try to build Ruby.  Here's the 
info:

>oslevel
5.2.0.0

>gcc --version
gcc (GCC) 3.3.3
Copyright (C) 2003 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR 
PURPOSE.

And here's the error I'm getting:

/usr/src/ruby-1.8.1>make
        gcc -g -O2   -I. -I.  -c array.c
In file included from ruby.h:671,
                 from array.c:15:
missing.h:81: error: conflicting types for `memmove'
/usr/local/lib/gcc-lib/powerpc-ibm-aix5.1.0.0/3.3.3/include/string.h:118: 
error: previous declaration of `memmove'
missing.h:95: error: conflicting types for `strcasecmp'
/usr/local/lib/gcc-lib/powerpc-ibm-aix5.1.0.0/3.3.3/include/string.h:237: 
error: previous declaration of `strcasecmp'
missing.h:99: error: conflicting types for `strncasecmp'
/usr/local/lib/gcc-lib/powerpc-ibm-aix5.1.0.0/3.3.3/include/string.h:238: 
error: previous declaration of `strncasecmp'
missing.h:112: warning: `struct tm' declared inside parameter list
missing.h:112: warning: its scope is only this definition or declaration, 
which is probably not what you want
missing.h:116: warning: conflicting types for built-in function `strstr'
missing.h:126: error: conflicting types for `strtoul'
/usr/local/lib/gcc-lib/powerpc-ibm-aix5.1.0.0/3.3.3/include/stdlib.h:183: 
error: previous declaration of `strtoul'
make: 1254-004 The error code from the last command is 1.

Any ideas?

-- Matt
Weinberg's Law: If builders built buildings the way that programmers wrote
programs, the first woodpecker that came along would destroy civilization.