XcodeColors is an easy-to-use SIMBL plugin for Xcode 3 & 4 developers. It was developed by Deep IT and it is absolutely free for any use (open source & commercial). This project is designed to simplify software debugging process by colorizing debugger console output.
What's new in version 1.0.6
XcodeColors uses the standard Xcode plug-in format, so you can just unzip it to ~/Library/Application Support/Developer/Shared/Xcode/Plug-ins, and rename to XcodeColors.xcplugin