NeoGAF reports that the update removes Fallout 3's SupportsCDKeyCopyToClipboard, ShowCDKeyOnLaunch, and legacy key registry functions -- all key components of Games for Windows Live integration. Blue's News finds that the game still installs the Games for Windows Live client upon launch, however. Uninstalling the client currently renders Fallout 3 inoperable.
Several games have ditched Games for Windows Live support in recent months, including BioShock 2, Batman: Arkham City, and Warhammer 40,000: Dawn of War 2. Several Microsoft-published PC releases and high-profile games like Dark Souls and Grand Theft Auto 4 still require Games for Windows Live to function.
[Update: A Bethesda spokesperson has contacted Joystiq with clarification regarding the recent update. "We have not removed GFWL from the game," the spokesperson stated. "The only that that has changed is that Steam has removed the need to activate the GFWL codes when purchasing the game."]