What is the license of the OS X SDK? The Xcode package contains files that get installed in /System and /usr. Is it possible to redistribute those files in a different package? What kind of what are the legal implications?
The license for Xcode is pretty easy to find from:


http://www.apple.com/legal/


Specifically, http://images.apple.com/legal/sla/docs/xcode.pdf

Like the rest of Apple's licensed software, it states in part that licensees may not rent, lease, lend, sell, sublicense or otherwise redistribute the software. The only exceptions I've seen is derivative work that includes licensed components as part of the build process and not by simply repackaging parts or all of Apple's software.

The legal implications vary by your jurisdiction and whether you have signed any other agreements with Apple that would amend or override the standard license terms. Common sense says you would want to either ask Apple directly or get a lawyer to assist you before redistributing licensed and copyrighted goods.

Also, you might check at http://opensource.apple.com to see if portions of the code are open-sourced or have other licenses. Worst case, you'll need to arrange a license agreement with Apple on the use in your case if it's not per the standard license.