Hi Cosrocket,
From what I can tell from all of the posts on macrumor and apple.com, it appears to be primarily the Seagate drive, however it may be that maybe no one with Western Digital drives are saying anything..
I have the Seagate drive, and EXACTLY as Kronie described (inconsistent noise for a few seconds then goes away) is what I am experiencing. I called Apple Care today and tried to describe the problem, and they asked me if the noise is loud.. Ok, so loud is a subjective term, I told him it is not "loud" per se, but it is noticeable... I them asked him what Apple's official position is regarding any noise, but he did not know the answer and had me do a hardware test which came out fine but heated the computer so hot I thought it would set itself on fire.. (-: He would not make a statement like Kronie was given regarding that the machine should be silent...
At this point I am going to wait on trying to replace my machine.. In my honest opinion, it sounds like it is doing what a hard drive does, it just does it louder than I am used to...
The strange thing is... it did not make a sound my first few days with the computer, even after doing a migration assistant conversion of about 60 gb of data from my old mac... Then three days later I started hearing it.. Also strange is that the longer the machine is on during the day, the quieter the noise is with less frequency!
I still plan on talking to a Genius at the Apple Store, as quite frankly I had a tough time understanding the Apple Care rep (I think they now provide support from India)...
Kronie, for what is it worth, knowing that two apple reps told you the machine should be dead quiet is what upsets me the most! I would almost rather hear from them "a little hd noise is normal, no problem"... Makes me wonder if I should attempt a replacement of the machine... I sit and look at this elegant beautiful machine with minimal to no fan noise, and am surprised that the hard drive they would use would make so much noise!