AFAIK this is the same on all new SR macbooks, they changed the DVD drive.
It was that quiet on my previous 2ghz macbook I couldn't hear it but now on my 2.2 SR macbook I can.
I was going to say I don't really care for it as I only have to reboot the macbook after VLC has crashed it when I play HD films but I just realised it does it when waking from sleep.
Its not that much an issue for me, when I changed macbooks I thought it was very loud but now its either quietened down or I have got used to it 🙂