A Cre8asite Forum thread named Google is testing a new Adwords format shows how the top three sponsored ads in Google SERPs are showing up different shades of background colors for one specific user (at least).
![adwords-colored-s.gif](https://www.seroundtable.com/archives/adwords-colored-s.gif)
The screen capture above is from the user reporting the new sighting. It is very possible that this is an other UI test by Google. But this can also be a spyware or adware attack. No confirmation from Google as of yet.
Update: Official Response from Google (Thanks Gary Price):
Looks like our older UI. We used to do ads in different (tasteful) colors. Note the old version of the tabs for (Web Images Groups Directory News Local). I suspect that this is just a screenshot from years ago. The tabs wouldn't look like that on a current UI test.