Apple has acknowledged two video problems in both the new MacBook and MacBook Pros, following past video problems with other MacBook lines. One of them seems pretty obvious. Called "the black screen of death", it happens when the graphic card goes into overload playing games, turning off video and locking up the system while the audio enters into a loop. Apparently it's a thermal issue, but Apple doesn't know if this is a hardware or software problem yet, according to an Apple Support forums member:

Just spoke to AppleCare UK and they also confirm "Apple are aware of the issue and are investigating. At present we do not know if this is a hardware or software issue and have been advised not to offer customers exchanges until the issue is better understood."

I've also read the posts suggesting this is a thermal issue but I got screen noise/distortion when just waking the machine from sleep and also monitored the fans while playing WoW and they were running at 6000+ rpm consistently.

Ultimately Apple have access to more testing resources and should come up with a fix fairly soon but if my replacement exhibits the same issues when it arrives in two weeks time, I doubt I'll keep waiting: I'll have it shipped back and ask for a re-fund until Apple sort this out and I can purchase a working computer.

The catch here is that it may be hardware-based and not software, because the problem happens under both Windows and Mac OS X.

Another problem seems less important, but users claim that it can be even seen in most systems at display in Apple retail stores: If you scroll a web page with HD video on it, there's a wave-like distortion affecting it. Apple says they are aware of the problem and they are working in a software patch that will solve the issue.