Sergey Alakov who must be included in every single Google tests bucket found another Google test where they are showing a floating button in the local listings that let you toggle between a map view or list view.
Here is a GIF where you can see the blue circle button at the bottom right switched the interface from map view to list view:
This allows searchers to find local results by proximity to a point on the map visually or by data.
I believe this map toggle button is something used in Google Maps as well.
Forum discussion at Twitter.
