Last week was a beta run of the update where you could opt in. Which apparently you are opted in. This week is the official release of an update to the main Beta. No changes were made between the two.
And yet when I check the "last modified" dates of the files, I find a few dated 09/11/2014. These are files that can only be obtained via Steam, so something had to have changed between 9/2 and 9/11.