Zephyr unit (HDMI + added heatpipe/heatsink contraption) from end of 2007 died sometime in middle of 2009. It fell under the 3 year warranty, and I got it replaced fairly quickly (two weeks). Got a falcon unit out of it, which still works, or at least until I traded it in sometime this summer (2011) and bought a 4GB slim + kinect, which I sold to a buddy of mine sans kinect. I actually ended up buying a 360 Slim 250GB at the end of 2010, which is now my only unit.
Can't say I'm surprised about the Zephyr unit conking out. I must have put in near two thousand hours between Gears, Halo 3, Bioshock, the Guitar Hero & Rock Band series, Dead Space, and Mass Effect (about 200 hours alone with several characters). It was just a matter of time with all that drive spinning and heat, especially with some days just playing 12 hours straight. I only played DOAX2 for about 10 hours. :3