I had a PowerBook G4 immediately prior to purchasing my MBP, and I remember it making the same noise. They're not the same product, but as with yours things were bad enough that when the volume was down low, that fan noise was louder than whatever was playing. It wasn't that bad when the system was new, but seemed to develop once the drive had received physical damage. In fact, the drive unseated itself Thursday and it was more cost efficient to buy an MBP than to fix it. Does your computer show any signs of physical damage? Mine did, and the internal components suffered as well as the casing.
My MBP doesn't make the fan noise like the PB did, just the unholy clicks and whirring that all of the MacBook SuperDrives seem to make when spinning up. Of course, it's also brand new. How old is your MBP, and has it been damaged? My PB started doing things before it was a year old, so it would be interesting to know if SuperDrives in general degrade quickly or if it's purely a matter of their 'health.'
My recommendation would be to schedule an appointment with the Genius Bar at your local Apple store, if you have one, because the noise is NOT normal. It's a lot better to take your machine in so the techs can actually hear/see what's going on. It's harder to deal with the issue over the phone. If calling AppleCare is your only choice, then do so, but they'll probably recommend letting someone have a look at it in person.
Quick note, if you take it in, make sure you bring some discs that you know cause the fan noise with you. Sounds silly, I know, especially when all of them do it, but I got chewed out by one particularly 'charming' technician for neglecting to do this.