Not really an issue....
You people are way too sensitive. There may be a *few* defective ipod touches, but most of the "examples" apper to just be an issue of viewing angles, or brightness adjustments. I looked at my Samsung phone, my video iPod, my iBook, and my 40" Samsung TV, and they all exhibit this to soem degree. Granted, the 40" TV appears to have the best viewing angle, but that's why it was $1500. No company is going to use the best LCD dislay for a 3.5 inch screen. My friend's baclberry does the same thing when held at an angle too. It is just a property of an LCD screen with a not so great viewing angle.
For those who are going "wait until this gets resolved", you'll be waiting a long time. My touch is awesome, I don't notice any black issue, I have no dead pixels (whch I think would be more of a problem), and it works flawlessly. I say enjoy the freakin' thing and quit looking for a reason to return it.