I too am having a "wakeup" problem with the 30" display just within the past week or so. You will probably notice the power light is flashing with 2 short and 1 long flash over and over. This is the code for "backlight failure". I too can recover by letting the system return to standby and trying again to wake it up. This happens only about 5 or 10 percent of the time on wakeup.
I talked to the Apple Care folks who reminded me of the very large power spike encountered with BOTH the Mac Pro and the ACD backlight when coming out of sleep or standby which could cause the power to briefly drop and the backlight to fail to light. Although they suggested stripping out most of my drives and memory and replacing the 1900 video card with the original 5300, I think my problem may be with my UPS.
I hadn't considered the UPS as I upgraded my computer and when I checked it out, I discovered it was only rated at 500VA, way below what should be running my current system. I had ignored the occasional overload beeps and the occasional warning message popup from the UPS indicating I was on battery power. I temporarily plugged the ACD directly into the wall socket and am in the process of replacing the UPS with a larger 1500VA (865 watt) unit. I have not encountered a display wakeup issue since changing the display power, and hope the new UPS will continue to show good results.
So ... before you panic ... check your AC power input path and make sure everything (UPS, surge suppressor, power extension cords) is up to the load you drawing. Next suspect would probably be the video card. The recent firmware upgrade would seem to be a long shot ... but if more users report this problem it may be suspect as well. Hopefully we won't have to send in our 30" displays to be fixed.
-howard