The waiting is painful. This could make the purchase decision really hard. I was about to buy the HL-T7288w, but the 67" with DarkChip4 may be worth the 15% smaller screen size.
I did notice a press release from TXN on DarkChip4 from september. That leads me to believe tha they've had the technology long enough for Samsung to use it in the 2008 models. I hope that's the case.
Maybe if they have the DarkChip 4 in the 72" 6 series (likely with a bulb), it may be worth? Too many choices, not enough information.