Custom Xcode templatesEdit
Factory templates can be found in /Developer/Library/Xcode/.
File templates
For example, the Cocoa Objective-C class template is stored at /Developer/Library/Xcode/File Templates/Cocoa Class/Objective-C class/Objective-C class.pbfiletemplate/.
To make a custom template, copy the appropriate .pbfiletemplate folder into ~/Library/Application Support/Developer/Shared/Xcode/ and modify it.
For example, I have a customized version of the Cocoa Objective-C class template that includes the BSD license boilerplate at ~/Library/Application Support/Developer/Shared/Xcode/File Templates/Cocoa Class/Objective-C class/Objective-C class with BSD license.pbfiletemplate/.
Project templates
Example:
/Developer/Library/Xcode/Project Templates/Framework & Library/Bundle/Cocoa Bundle
Becomes:
~/Library/Application Support/Developer/Shared/Xcode/Project Templates/Framework & Library/Bundle/Cocoa Bundle