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.
Google is testing a translucent Google Feed page on the Pixel Launcher was written by the awesome team at Android Police.