For people like me, that updated to XCode 4.3 and delete the older versions of XCode you may have noticed some strange errors in you develop tools.
The reason for this is that Apple decide to make the command line tools an optional download and change the location of the same.
After you download the tools trough XCode->Preferences->Downloads->Command Line Tools just run this command:
sudo /usr/bin/xcode-select -switch /Applications/Xcode.app/Contents/Developer/
This will set the default xcode folder for other tools to find.