It probably is the processor.
My new Macbook has a bit of processor whine. And it's a week 39 build, so I'm sure that by now the problem has been addressed as much as it can be.
I was a little disappointed at first, but the more I read about it, it sounds like it's kind of the nature of the beast, and I'm quite happy with the Macbook otherwise. I've heard that people hear this noise even on non-Apple notebooks with Core Duos. Some say they have a Core Duo Windows machine and can't hear any noise, but I bet that's mostly because the fan noise covers it up.
Anyway, if you send it to Apple, they will probably replace the logic board, and you may get one that's just as noisy because even the "fixed" logic boards have this whine to some extent. It's just not as bad as it used to be.
Don't worry about it too much unless it's REALLY loud or your MB starts acting up in other ways.
P.S. Check your Macbook's build week (the 4th and 5th digits of the serial number). If it's around 30 or above, than I doubt you have a unit that would actually benefit significantly from a logic board replacement.
P.P.S. Ask yourself how bad the noise REALLY is. Sometimes these kind of things seem way worse than they are because once you notice them, you can't stop thinking about them for a while...
