Browsing works but some functionality is broken; for example you can't view your order history.

I do recall reading somewhere that Amazon.com isn't actually hosted or fully leveraging on the AWS platform, mostly due to the political struggle between the AWS and the merchant department.

Sales Department: "We require 100% uptime! Can you do that?"

AWS Department: "Wellll, if we don't change the status to red, it's as if we were up all the time!"

There are public talks on Youtube from Amazon.com titled "Drinking our own Champagne" where they say the opposite.

Yeah, that was the original pitch for AWS. Engineering presentations since the initial launch have included "yeah... not quite" admissions though.

The ability is there for any company to take advantage of multiple regions. Takes time and money, but it's doable.