After installing XCode in Mac OS X Lion, I could not compile any programs using gcc. I had no Developer folder, and command line compiling returned an error - "gcc: command not found." Here's how I fixed it:
In Xcode, go to: Preferences -> Downloads with "Components."
Find Command Line Tools, and click on install. After entering your password and your Apple Developer userid and password, the command line tools gets downloaded and installed, including gcc.
That's it!
