Ok cool, thanks. I already knew the theory behind it. I was just wondering if there were any instances where the DVD production companies tried to compensate for this. I guess the answer is no.
I always knew PAL DVDs played 4% too fast, but I never really paid much attention to that fact. Then I was watching the PAL version of Lord Of War which I bought recently (since the Canadian/US version has the aspect ratio screwed up) and I noticed that the song during the credit sequence, "For What It's Worth" by Buffalo Springfield, was about a semitone too sharp! Luckily, a simple click of "PAL TruSpeed" in WinDVD fixed the problem.