brew install ruby-enterprise-edition

ruby-enterprise-edition.log

/usr/bin/cc -g -O2 -O3 -march=core2 -w -pipe -pipe -fno-common    -DRUBY_EXPORT  -I. -I. -I/usr/local/Cellar/readline/6.1/include -D_XOPEN_SOURCE -D_DARWIN_C_SOURCE   -c main.c
/usr/bin/cc -g -O2 -O3 -march=core2 -w -pipe -pipe -fno-common    -DRUBY_EXPORT  -I. -I. -I/usr/local/Cellar/readline/6.1/include -D_XOPEN_SOURCE -D_DARWIN_C_SOURCE   -c dmydln.c
ar rcu libruby-static.a array.o bignum.o class.o compar.o dir.o dln.o enum.o enumerator.o error.o eval.o file.o gc.o hash.o inits.o io.o marshal.o math.o numeric.o object.o pack.o parse.o pointerset.o process.o prec.o random.o range.o re.o regex.o ruby.o signal.o sprintf.o st.o string.o struct.o time.o util.o variable.o version.o  dmyext.o
/usr/bin/cc -g -O2 -O3 -march=core2 -w -pipe -pipe -fno-common    -DRUBY_EXPORT  -L. -L/usr/local/Cellar/readline/6.1/lib   main.o dmydln.o libruby-static.a -L/opt/local/lib -Wl,-rpath,/usr/local/Cellar/ruby-enterprise-edition/2011.03/lib -L/usr/local/Cellar/ruby-enterprise-edition/2011.03/lib -lsystem_allocator -ldl -lobjc   -o miniruby
./ext/purelib.rb:2: [BUG] Segmentation fault
ruby 1.8.7 (2011-02-18 patchlevel 334) [i686-darwin11.0.0], MBARI 0x6770, Ruby Enterprise Edition 2011.03

make: *** [.rbconfig.time] Abort trap: 6
Exit status: 1

http://github.com/mxcl/homebrew/blob/master/Library/Formula/ruby-enterprise-edition.rb#L24

==> Environment
HOMEBREW_VERSION: 0.7.1
HEAD: 857678439f00f7c2311275ca4a0e8d0fd119c236
HOMEBREW_PREFIX: /usr/local
HOMEBREW_CELLAR: /usr/local/Cellar
HOMEBREW_REPOSITORY: /usr/local
HOMEBREW_LIBRARY_PATH: /usr/local/Library/Homebrew
Hardware: dual-core 64-bit core2
OS X: 10.7
Kernel Architecture: i386
Ruby: 1.8.7-249
/usr/bin/ruby => /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby
Xcode: 4.1
GCC-4.0: N/A 
GCC-4.2: build 5666 
LLVM: build 2335 
MacPorts or Fink? false
X11 installed? true

==> Build Flags
CC: /usr/bin/cc => /Developer/usr/llvm-gcc-4.2/bin/llvm-gcc-4.2
CXX: /usr/bin/c++ => /Developer/usr/llvm-gcc-4.2/bin/llvm-g++-4.2
LD: /usr/bin/cc => /Developer/usr/llvm-gcc-4.2/bin/llvm-gcc-4.2
CFLAGS: -O3 -march=core2 -w -pipe
CXXFLAGS: -O3 -march=core2 -w -pipe
CPPFLAGS: -I/usr/local/Cellar/readline/6.1/include
LDFLAGS: -L/usr/local/Cellar/readline/6.1/lib
MAKEFLAGS: -j2

PKG_CONFIG_PATH: /usr/local/Cellar/readline/6.1/lib/pkgconfig
Error: Failure while executing: ./installer --auto /usr/local/Cellar/ruby-enterprise-edition/2011.03 --no-tcmalloc -c --with-readline-dir=/usr/local/Cellar/readline/6.1
Please follow the instructions to report this bug at: 
https://github.com/mxcl/homebrew/wiki/new-issue

Also try:
  `brew doctor` to check your setup for common problems.
  `brew missing` to check installed packages for missing deps.
$ 

For posterity:
brew install ruby-enterprise-edition --use-gcc

https://gist.github.com/jcamenisch/ae88c6cf86b0c1432260