What happened to the code?

Amazon Web Services is moving code hosted at GitHub to a new GitHub organization: http://github.com/aws. Nothing is lost. Only moved.

What do I do now?

Simply update the URL of the repository's origin:

First, back up a few commits:
$ git reset --hard d005dde1ac04566d9564b36436aa8f2f8db7657b

Next, change then URL of origin:
$ git remote set-url origin git://github.com/aws/aws-sdk-ruby

Verify it worked
$ git remote -v

Pull the latest changes
$ git pull

Lastly, move your local repository to the new name (without the "for")
$ mv aws-sdk-for-ruby aws-sdk-ruby