At Xeno’s request, I’ve installed Ruby 2.0.0 on Shellx.  However, because there were 128 things dependent upon the existing ruby, rather than overwriting the system version, I’ve installed 2.0.0 in /usr/local, the executable is in /usr/local/bin.  If you want the newer version, either specify the full path or make sure that /usr/local/bin is before /usr/bin in your $PATH variable.