I recently purchased a new MBP 15, 3 Ghz, 500 GB 7200 rpm hard drive, build-to-order. The hard drive appears to be a seagate ST9500420ASG. I am experiencing a strange hard drive click followed 80% of the time by a beep. It is definitely not a beep from the speaker. Additionally, it happens at any time, even when the computer is sitting on a perfectly still table. It is exactly the same sound as what is documented at
and mine too appears randomly approximately 15-20 times per day. It does not appear to matter if the computer is under light or heavy use and it seems truly random when it occurs. Another user on youtube has also experienced this with their new MBP 15 and sent me a wav file with the same sound mine is making. So far, his experience is that it does NOT occur under bootcamp. This leads me to believe that it is something specific to OSX. Turning off the "put hard drive to sleep when possible" does not seem to make any difference. I have not personally tested bootcamp on my machine to confirm that mine is the same, but the original poster of the youtube video linked above also seems to think it is OSX specific.