First, make sure you ran the XCode installer that was downloaded from the AppStore. Then run the Mac OS X 10.7 gcc installer
gcc-4.2 is listed
$ ls /usr/bin | grep gcc gcc gcc-4.2 i686-apple-darwin11-gcc-4.2.1 i686-apple-darwin11-llvm-gcc-4.2 llvm-gcc llvm-gcc-4.2
Install Ruby 1.9.3 Success!!
$ rvm install 1.9.3 Fetching yaml-0.1.4.tar.gz to /Users/mdesilva/.rvm/archives Extracting yaml-0.1.4.tar.gz to /Users/mdesilva/.rvm/src Configuring yaml in /Users/mdesilva/.rvm/src/yaml-0.1.4. Compiling yaml in /Users/mdesilva/.rvm/src/yaml-0.1.4. Installing yaml to /Users/mdesilva/.rvm/usr Installing Ruby from source to: /Users/mdesilva/.rvm/rubies/ruby-1.9.3-p0, this may take a while depending on your cpu(s)... ruby-1.9.3-p0 - #fetching ruby-1.9.3-p0 - #extracted to /Users/mdesilva/.rvm/src/ruby-1.9.3-p0 (already extracted) ruby-1.9.3-p0 - #configuring ruby-1.9.3-p0 - #compiling ruby-1.9.3-p0 - #installing Removing old Rubygems files... Installing rubygems-1.8.10 for ruby-1.9.3-p0 ... Installation of rubygems completed successfully. ruby-1.9.3-p0 - adjusting #shebangs for (gem irb erb ri rdoc testrb rake). ruby-1.9.3-p0 - #importing default gemsets (/Users/mdesilva/.rvm/gemsets/) Install of ruby-1.9.3-p0 - #complete