Gears of War 2 has been available for a few days to a small percentage of gamers that have a modded xbox and tons of glitches have been popping up recently on youtube. Many of those will give you advantages over the opponent therefore ruining the Online Multiplayer experienced for many. This is just the beggining of the glitches that will be found.
A few weeks before the game releases they start making the millions of copies of the disks in factories and some of those employees steal them and rip them into their computer and upload them to the Internet thats how I know this comes from an exact copy of the retail version. Either way look at the good side of this if Epic notices all this glitches they might have a patch ready by the time the game comes out.