Hey guys,
I've been having the same problems as the rest of you all. I have a 2.4 MBP 15" (1st gen unibody) and experience intermittent, but intense flickering on the top half of the screen, ONLY on the 9400 integrated chip. I only encountered this problem after taking in my MBP for repair on the audio port, which was stuck on optical out. After the repair (replaced logic board), the flickering began.
I took the "fixed but rebroken" machine into the Apple Store, where they assured me it was the hinge assembly, even though I pointed out and demonstrated that the integrated graphics chip was the problem. After letting them do their thing, I got back a repaired machine. They had simply replaced the clamshell around the display (a $625 item!!!) and the hinge assembly. Sure enough, after 5 mins of use, the screen had flickered. It almost seems worse.
Anyways, I called Apple today, voicing my displeasure at their failure to actually diagnose the problem or take note of my own diagnosis. The rep forwarded me to a senior consultant, who asked me some very specific question. This guy was obviously familiar with the issue, as he asked me questions about whether it was reproduced on the high-performance setting, etc. After our conversation, the rep agreed that it should be repaired under warranty (my warranty expired while it was getting repaired the 1st time for the audio port), since the problem didn't occur until I got the machine back.
I'm hoping this time that Apple will get it right and fix the issue. It sounds like you just need to get through the chain of command to someone who knows about this issue. Otherwise, it's diagnosed as something completely unrelated to the real problem -- the 9400 gfx chip.
Good luck to the rest of you, and I'll update everyone as to how this repair goes.
