This excerpt taken from the THQI 10-Q filed Feb 9, 2006.
3. Xbox 360 Development Kit License
Publisher shall enter into one or more development kit license(s) for the applicable territory(ies) to which Xbox 360 game development kits will be shipped for use by Publisher (each an XDK License) pursuant to which Microsoft or its affiliate may license to Publisher software development tools and hardware to assist Publisher in the development and testing of
Software Titles, including redistributable code that Publisher must incorporate into Software Titles pursuant to the terms and conditions contained in the XDK License.