A Gears of War title that uses Kinect isn't confirmed yet, but it's becoming more likely that one exists.
Kotaku reports that "sources claiming to be familiar with the project" say it definitely exists and is under development. The associated screenshot is evidently from an older concept demo of the Gears of War Kinect game, showing a player touching his ear to use a communicator, with Marcus Fenix also performing the action in-game.
A source also said that while the implemented Kinect functionality may not be fully worked out yet, the game will likely be an on-rails shooter. This means that players would have little to no control over the movement of their character, and would presumably use their hands to aim and shoot at enemies.
Epic Games designer Cliff "CliffyB" Bleszinski already confirmed that Gears of War 3 wouldn't use Kinect, so unless he's lying the rumors refer to a separate product. A game called Gears of War: Ultimate recently popped up in GameStop's online database, but that turned out to be the Gears of War: Triple Pack.
Siliconera noticed a trademark for Gears of War: Exile in early 2011, which is our only hint toward the title of Epic's Gears of War Kinect game. Recent rumors also put Halo down for some kind of Kinect conversion, so I'm expecting at least one hardcore Microsoft-exclusive franchise to use the device by the end of the year.