I just got five Raptors, and each and every one makes a high pitched whine that drives me nutz. Either I've become immune to it after a few days, or they have quieted down a bit since the first install, I dunno, but it seems not as bad once I've been around them for a while. In my RAID config w/ 4 Raptors on it, I notice definite "hot" spots and "cold" spots for that high-pitched tone, where if I put my head in one place it vanishes, but if I move it two inches to the left it comes back double strength.
IMO though, the noise is worth it for my RAID rig, where I needed a good performance-per-price ratio.