Amazon has also done their share of damage to their affiliates over the past two years. I don't think Amazon is very serious about their affiliate program any longer. Between the loss of the user reviews from the feed, to the rationing of queries, they have made it difficult to be an affiliate who operates multiple XML feed sites. When they first started rationing queries, my sites wouldn't stay up for more than 20 minutes because I had tons of traffic and spider activity. I had to severely curtail the spider activity in order to keep the sites up.
Do a site query command to see if your Amazon site has been de-indexed. When it is completely de-indexed the PR also drops to n/a.
I checked a friend's Amazon sites a few hours ago and almost half of his sites are gone from Google's index. Only two of my sites were de-indexed, but the rest were losing pages rapidly, so I shut them all down. After the domains cool off for a few months I will use them for something else.
My big question is, "Will Google butcher data feeds sites from their Google Affiliate Network?" Those sites have the same duplicate content issues that the Amazon data feed sites have. I have several sites running their data feeds and will be watching them. If they do not penalize their own affiliates, Amazon could have a good legal case against Google.
"Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote." -- Benjamin Franklin