I'm in the UK. I bought my 2nd MBP in May 2009 and I dont know when I noticed this flickering, but it was last year sometime. In February I could no longer stand it so rang apple and they said take it to a repairer and it may have to have a new logic board and display. The repair shop hadnt heard of this flickering before (!!!) and also couldnt see it but did as apple said - and they tested it and said all was OK. I picked up it without testing it in the shop - but when I got home, started it up, it was there - not only there but 10 times worse.
I couldnt do without it for about 6 weeks, even if the flickering was driving me mad but I managed to get a short film of it, put it on my desktop ready for it to go to apples suggested repair shop. Off it went, had a new logic board just this time I think - got it back and the screen was totally covered in pink lines - so back it went.
Another new logic board went in but while they were testing it, the hard drive went.
So I got it back and apple agreed to replace it.
Unfortunately though, the new MBP I got last week was also faulty - so I'm getting another one.
It took some getting going, but in the end I found THE most helpful Technician (the one before disappeared) who is British and understands my trying to explain what's going on as I'm not very technically minded to say the least.
So, although I was moaning about apple to begin with, they are sticking with me. When I get this new one I think I'll do the extended warranty because although I've had apple for about 6 years and never needed it - I'm not that confident to cope alone!
Just keep on to apple if your machine is in warranty - although I cant suggest what you do if it's run out. Maybe if apple dont keep an eye on here really, write personally to the man in charge!!!