I was thinking about asking the same question concerning my '01 SSEi with 55k. Over the Winter I noticed a very slight shrill whine/squeek coming from the same area when I rev the engine a bit. I thought it might be the belt (replaced with a Gatorback = no luck) although it sounds like it'* coming from the rear of the alternator when I used a stethoscope. When I replaced the belt I spun all the pulleys, SC, etc. Sounded like the rear alternator bearing was the culprit when I spun the alternator pulley. Now I'm not so sure. When I scope the SC (just replaced the nose cone about 8 months ago due to leak) it sounds like it may be coming from there, but when I listen without the scope the noise points to the rear of the alternator.
2001 SSEi- black; stock 92K
1995 Vette; Competition Yellow; stock; 38K