"Your Message Center shows you messages from Amazon.com that are generated based on your Favorites, your wishlist, and your community settings."
Amazon already sends email notifications based on user requests (you can be warned when a product is available for order, or when a search query turns out new results). Now they introduce this "message center" page that consolidates notifications based on your profile, and looks like an e-mail client (not unlike what CJ does in the affiliate field). I’m surprised that Amazon.com, besides e-mail and web pages, doesn’t offer push options to IM clients.