Just a fwiw, been out of the country for a while, for those new to this thread:
My 46G10 has about 1800 hours on it. Using an enhanced Spyder3, I have seen no increase in measured black levels since my first calibration at about 140 hours.
Also, I have a brand new 54G10 that has less than 50 hours on it (I've not been able to run the breakin slides do to being away for a while.) When I put the two TVs side by side, with the same video running on both, same patterns, etc. I cannot see a difference between the 50 hour G10 and the 1800 G10.
I am NOT saying that Orta or anyone else doesn't have a real issue. Just saying for those who are claiming this happens to all G10s - it apparently doesn't. Maybe it will happen to mine in the future, but not so far. I love the picture on my G10s at least as much now as I did when I first got them.