Sounds like the same issue I've seen on my 17" Unibody, which seems to have been fixed by the firmware update released yesterday (so far, at least - it's only been a day). I had either a full screen or partial (like 1/4 or 1/3) which would "blink" black. Sometimes, I could actually see the redraw, but it's basically a flash of black.
If you're on the 9600, try switching back to the 9400. I only had the problem with the 9600, and it was triggered by wakeup. I also never saw it when running in BC on XP.
I'm going to make a guess that there will be a firmware update for the 15" as well (especially, since there was one in Jan., which got pulled). There are some YouTube videos of 15" UB's with the problem.
I had the option of exchanging my 17", but all the evidence was pointing to a software problem and I didn't want to risk losing my otherwise perfect machine (to dead pixels or ?). So, my feeling is to hang in there.