This excerpt taken from the ATVI 10-Q filed Feb 8, 2006.
Branding Specifications. Publishers use of the Licensed Trademarks (including without limitation in FPUs, Online Content and Marketing Materials) must comply with the Branding Specifications set forth in the Xbox 360 Publisher Guide. Publisher shall not use Licensed Trademarks in association with any third party trademarks in a manner that might suggest co-branding or otherwise create potential confusion as to source or sponsorship of the Software Title,Online Content or FPUs or ownership of the Licensed Trademarks, unless Microsoft has otherwise approved such use inwriting. Upon notice or other discovery of any non-conformance with the requirements or prohibitions of this section, Publisher shall promptly remedy such non-conformance and notify Microsoft of the non-conformance and remedial steps taken.