Mine has the date 12/12/05 printed on the back of it (I bought it used a couple of weeks ago), and it's working fine. I am a bit worried though, since Gears is starting to have more framerate issues and it's freezing for a couple of seconds at a time in some parts on my second playthrough. The disc is intact and it played with no hitches on my first playthrough.
Microsoft had better fix this hardware failure issue as soon as possible. When almost everyone who owns the console is worried about the thing spontaneously breaking down on them, it makes the company look pretty crappy. It pisses me off that such a great, fun and well-made system like the Xbox 360 would be well...not so well-made!