I’ve not used Ruby a great deal, in fact I installed it many years ago with the intention of learning Ruby on Rails (oh so on trend) and then decided I couldn’t be bothered.
I wanted to try using Forward, a service getting your local domain out on a public DNS to find it is a gem you have to install and it wouldn’t install on OSX Lion.
Install XCode command line tools
The first thing is that xcode is getting in the way. incredible I know, but there we have it. There are now command line tools and these are not installed by default. You will need to install this 185MB download from inside xcode.
Open xcode and go to Preferences. Choose the Download tab and install Command line tools.
You can also now set up automatic updates if you haven’t already (I would).