Macfixit has an article regarding Snow Leopard and display profile issues. It's here:

reviews.cnet.com/8301-13727_7-10384201-263.html?tag=mncol;txt

According to the article, a fix may be in the works for the upcoming OS update, 10.6.2. It may be that some of the reported problems in calibrating the newer iMacs may be down to Snow Leopard instead of the machinery.