Since you are a kick-ass developer, you own a Macbook Air (most of us do) yet, you are constantly pressed for moah hard drive space. With Xcode being a bit "portly", "there has got to be a better way"...to do stuff. The kick-ass peeps at Thoughtbot have a wonderful post walking someone through setting up a sweet Ruby dev environment on a brand new, Mountain Lion powered Mac.
Once that is done, send some sweet traffic to this post. It walks through some needed tweaks when running the homebrew-dupes version of gcc. Finally, run this command in your favorite shell to tell NVM (and other "items of importance") where your Xcode installation "resides":
sudo xcode-select -switch /usr/local/bin
Now when you run
nvm install v.0.x.x it won't fail because you feel
Xcode is a bloated pig and it doesn't deserve your hard drive's
time-of-day. In addition, you have a lean, mean way to build some really
cool shit with two awesome languages.