Things went very smoothly.  I did 
./configure --prefix=/scratch/hgs/local ; gmake && gmake check
The only noteworthy things were:

gcc -g -O2  -I. -I.ext/include/sparc-solaris2.9 -I./include -I.  -DRUBY_EXPORT  -c pack.c
( \
          gperf --output-file=lex.c.tmp -C -p -j1 -i 1 -g -o -t -N rb_reserved_word -k1,3,$ keywords && \
          cp lex.c.tmp lex.c && \
          mv lex.c.tmp "./lex.c.blt" \
        ) || \
        cp "./lex.c.blt" lex.c
/bin/sh: gperf: not found


Might be nice if configure could detect this and complain if it is fatal.

compiling openssl
sh: gnome-config: not found
compiling probeprofiler

We don't have gnome.  Probably fairly minor.

**   Ruby is compiled with --enable-pthread, but your Tcl/Tk library
**   seems to be compiled without pthread support. Although you can

I'll look into that, depending on what expect(1) needs.


ke[1]: Entering directory `/export/home/Scratch/hgs/ruby/ext/tk'
gcc -I. -I../../.ext/include/sparc-solaris2.9 -I../.././include -I../.././ext/tk -DRUBY_EXTCONF_H=\"extconf.h\"  -DWITH_TCL_ENABLE_THREAD=0 -fPIC -g -O2  -c stubs.c
In file included from ../.././include/ruby/ruby.h:24,
                 from stubs.c:2:
../../.ext/include/sparc-solaris2.9/ruby/config.h:19:1: warning: "_FILE_OFFSET_BITS" redefined
In file included from /usr/local/lib/gcc/sparc-sun-solaris2.9/4.1.1/include/iso/stdio_iso.h:44,
                 from /usr/local/lib/gcc/sparc-sun-solaris2.9/4.1.1/include/stdio.h:36,
                 from /usr/local/include/tcl.h:158,
                 from stubs.h:1,
                 from stubs.c:1:
/usr/local/lib/gcc/sparc-sun-solaris2.9/4.1.1/include/sys/feature_tests.h:105:1: warning: this is the location of the previous definition


Will probably disappear if I rebuild tcl/tk/expect.

And the tests ended with 


sample/test.rb:path .......................
sample/test.rb:gc ....
test succeeded

test_method.rb .............................................................................................................................................................................................................
test_objectspace.rb .
test_syntax.rb ....................................................................................................................
test_eval.rb .....................
test_knownbug.rb F.bootstraptest.tmp.rb:2:in `require': no such file to load -- continuation (LoadError)
        from bootstraptest.tmp.rb:2:in `<main>'
.
test_flip.rb .
test_block.rb .............................................
test_literal.rb .................................................................................................................................................
test_exception.rb ...............................
test_massign.rb ................................
test_proc.rb ..................
test_class.rb .........................................
test_thread.rb ....................
test_flow.rb ...........................................
test_jump.rb ........................
#344 test_knownbug.rb:6:in `<top (required)>':
     r, w = IO.pipe
     t1 = Thread.new { r.sysread(1) }
     t2 = Thread.new { r.sysread(1) }
     sleep 0.1
     w.write "a"
     sleep 0.1
     w.write "a"
  #=> not finished in 1 seconds  [ruby-dev:31866]
FAIL 1/746 tests failed
gmake: *** [btest-miniruby] Error 1
brains hgs 42 %>


I hope this is of use to someone.
In case it matters:
brains hgs 42 %> gcc --version; gmake --version
gcc (GCC) 4.1.1
        [...]
GNU Make 3.81
        [...]

This program built for sparc-sun-solaris2.9
brains hgs 43 %>

        HTH
        Hugh