I am not using the full Xcode package on my laptop. Instead I'm using the command line tools, offered by Apple as a separate and much smaller install. I haven't had too many issues, aside from not being able to use the FileMerge program that ships with Xcode. I never thought I'd miss it. But compared to other merge tools out there, FileMerge rules.

Anyway, a frequent issue I run into is when installing Ruby with RVM, it complains with

The provided compiler '/usr/bin/gcc' is LLVM based, it is not yet fully supported by ruby and gems, please read `rvm requirements`.

The solution (which I found on this Stack Overflow Thread) is to tell RVM which compiler to use.

 rvm install 1.9.3 --with-gcc=clang 
 rvm install 1.8.7 --with-gcc=clang
 ...

You may still receive a notice things may not work as expected, but I haven't run into anything yet.