Add me to the my 'Lamp' just died list! I have a WD-57831, purchased on 11/26/07, installed on 12/5/07, Lamp died on 07/05/07, Lamp life = 7 months, 0 days. This is FAR short of the 10,000 hours that is quoted. I did submit a claim to for a warranty replacement through Mitsubishi, and they claim it should be shipped to two to three days.
I have tried to go through 290 pages of this thread to get a gauge on how long the Lamp should last, but most people here seems to get far less than 1 year of usage, at $250 for a replacement Lamp this TV is going to get very expensive. I searched ebay and other sites and can get a replacement Lamp (Lamp only not the cart.) for approx. $180 shipped which is a little better but still makes this TV a consumables Hog!!!