Apple Addressing iPod Touch Screen Issue
Walt Mossberg reviewed the iPod touch and notes that its battery life falls short of the other iPods.
He also describes the screen issue that has affected "a small number of" iPod touch screens, and notes that Apple is addressing it:
Also, some early iPod Touch units have had defective screens, where images appeared too dark. Apple says this problem affected a small number of units and is being remedied. My two test units displayed beautiful images.
There's been no indication how many units have been affected, but an informal poll showed it affected 30% of iPod touch respondants. This is likely an overestimate as affected owners are more likely to seek out these forums/polls.
Anecdotal reports from the newest iPod touch buyers indicate that the problem may have been solved.