I bought my 8500UB in March, 2010, and I am now on my 5th lamp. The first quit working at 1,400 hours, the second at 1,200 hours, the third at 700 hours, and the fourth at 800 hours. Each time, the brightness began dropping quickly a few weeks before it quit turning on with a red error light. The bulb is getting so hot that it starts drooping, causing the brightness to decrease and eventually stop turning on, but the projector has never shut off for getting too hot. My typical usage is three hours a day.
The fourth lamp died last week, 14 months out of warranty. Epson sent me a new lamp for free, and all of the other replacements were also sent to me for free from Epson. I can't complain about their service, but this lamp model seems to have a short life in all of the projectors that use it. I've been told every time I call that they're aware of lamp issues and the new lamp I'm being sent won't quit working prematurely. They act like the problem has been identified and corrected. However, the lamp that came with the projector had the longest life at 1,400 hours.
I'll be upgrading to a 3D projector soon, and thankfully it looks like the newer Epson projectors don't have this problem.