A developer build of Gears of War 3 appears to have leaked onto the internet after having privately circled certain websites for a number of weeks. A user called ANONYMOUS360 has been responsible for making the leak public, and the game measures around 8GB after extraction: roughly accurate for an Xbox 360 game. ANONYMOUS360 also provided a video on his YouTube channel to confirm the legitimacy of the leak, using a JTAG Xbox 360 console in order to boot into the third title in Epic Games' series.
As one of the flagship series for Microsoft's console, the leak could cause some damage to its appeal, though it is only usable with JTAG consoles at the moment. Should it remain usable only via JTAG consoles then the issues presented by the leak are minimal at best, owing to the fact that JTAG consoles are unable to access Xbox LIVE for long periods of time. Users of Digiex have taken screen-captures from the video uploaded, which is almost definitely going to be taken down soon.
There are still some issues with the game, such as bugs with the video cutscenes. The game is not scheduled to release for two-and-a-half months, but it apparently is still playable through to the end. The leak is limited in its danger, but it may still lead to people leaking the ending of the game. The video uploaded by ANONYMOUS360 has since been removed due to copyright infringement, unsurprisingly.