It looks like Amazon might have fallen into the trap of employing Twitter just because they can. On the right margin of the page when logged in as an Amazon Affiliate is this box (right) letting affiliates know they can tweet an affiliate-coded Tweet directly from Amazon. In other words, the Amazon affiliate's Twitter followers will receive a Tweet linked directly to an Amazon product that the affiliate earns a commission on.
There's nothing wrong with using Twitter to alert followers to items on which commission is earned, but (in my humble opinion) it's hard to add value to a broadcast Tweet of a product anyone can see on Amazon. Yes, the affiliate could send a direct Tweet I suppose, but most people savvy enough to be an Amazon affiliate know how to communicate directly with a prospect about an available product.
To me it looks like a clumsy attempt by Amazon to Tweet for Tweet's sake.
Or do you think I'm missing something here?