Google has been tweaking the Google Feed (previously known as Google Now) page quite a bit recently. They started rolling out a dual-tabbed interface in December, but seemingly stopped shortly after. Last month, a new transparent Google Now pane appeared for one user, and now a modified version has showed up.
From left to right: Current UI, transparent UI, new translucent UI
The new design has a translucent background instead of a fully transparent one, which is definitely an improvement in my opinion. The only other change seems to be the removal of the quick access toolbar, but that could simply be a result of this user not being enrolled in the same server-side trial.
The changes only seem to affect the Google Feed page on the Pixel Launcher, the actual Google app hasn't been altered (yet). Let us know in the comments if you have the new Feed interface.