Matt's right. Most all the Canon A-series cameras have shutter squeal. It doesn't seem to affect performance, tho, at least it hasn't in mine.
Mine squeals about 60% of the shots I take, so I don't use it in quiet situations. They're still really nice cameras if you want a completely manual SLR. The other advantage is that really good lenses for the A- series can be had for a fraction of the price of their AF counterparts. I got a 135mm f/2.8 for my AV-1 for $25. The 135mm for my EOS system was over $250.