Previously, you could customize the colors of the search results in AdSense for Search, while the ads surrounding the results remained the usual default AdSense colors. Well now, you can change the colors of the ads to blend them in with the colors of your search results.
According to the AdSense Blog...
We're taking themes one step further. Each theme now has ads displayed with a look and feel that match the overall style used for the search results.
The result is harmony between search results and ads, which we think makes for a great user experience.
This should be a welcome enhancement to publishers who use AdSense for Search, considering the data showing that CTR tends to increase when ads are blended in with a website's color scheme.
Just wondering why it took so long for AdSense to roll this out!