A few weeks ago we reported Google was testing purple ad labels for AdWords. Well, it seems like this is not a test, but rather the ad label color of choice for the Google Maps listing results.
A help document at Google confirms they are purple, saying "Ad locations appear on the map with a purple icon and business name." Adding "if someone clicks the purple icon or your ad in the search box, your ad will expand to show details about your business."
They even shared both mobile and desktop screen shots of the purple ad label in the maps results:
So purple labels for map ads seem to be official. Yes, Google is testing green ad labels on desktop instead of the yellow ad labels.
Forum discussion at Twitter.