From about_xcode_3.2.1 PDF;

Xcode 3.2 developer tools for Mac OS X 10.6 has the following improvements:
• Static code analysis is fully integrated within the Xcode IDE via the Build and Analyze option under the Build menu or via custom build settings
• New Build Results window collects warnings and errors in a persistent log
• GCC 4.2 is the primary system compiler for the 10.6 SDK
• The next-generation LLVM compiler is included using two different front ends - the Clang compiler is a new, leading-edge front end that also provides the basis for the new static analyzer. For maximum compatibility, the GCC LLVM compiler utilizes the LLVM back-end with the GCC 4.2 front-end parser.
• New template chooser and project assistants • New opening window for quick access to recent projects