The error :
make[1]: *** [readline.o] Error 1
make: *** [all] Error 1
Error running 'make ', please read ...make.log
Snow Leopard version is 10.6.5
1) Make sure you have the latest XCode installed. I have 3.2.5
2) rvm update && rvm reload
3) rvm_archflags="-arch x86_64"
4) rvm install ruby-1.8.7
Fixes the problem and installs ruby-1.8.7-p330.