I installed Xcode but I still don't have gcc in my terminal
Great question — this recently changed, so I suspect many other people are wondering the same thing.

In the latest version of Xcode, the command line tools are distributed as a separate package. Luckily they're very easy to install:


Open Xcode, and open the Preferences window (⌘+,).
Switch to the Downloads tab.
Click "Install" (or "Update") next to "Command Line Tools". You can also configure automatic updates, and additional Xcode components.


Note: since these tools are actually a completely separate package, you can install the command line tools without installing Xcode, if you don't need Xcode and want to save some disk space. They can be downloaded separately from the Apple developer site.