Update: As of this morning the Xbox.com support page says the service should be back up to speed.
Updating you from our story a few hours ago comes new information regarding the state of Xbox Live. A little under an hour ago Microsoft and Activision have acknowledged the issues that have plagued the Xbox Live and Xbox Live Marketplace services. A notice was posted on the Xbox.com support page as well as the above message found on the Game of the Year Map activation page for Call of Duty 4: Modern Warfare.
While no formal reasoning is given the community finger has points squarely on the Variety Map Pack for Call of Duty 4 that released earlier today. Even though we're assured via Twitter, "the team is aware of issues w/ LIVE" from Xbox Live's Major Nelson, we wonder how the service will cope on April 29 as the world attempts to experience Rockstar's Grand Theft Auto IV.