Google Testing New Adsense Ad Formats

Google has been testing some new ad formats of Adsense in lat few weeks. Here is one screen shot from one of my blog.

Image Credit: Google

As we can see there are black dividers between ads with similar borders on either sides.

I am not sure whether these ad formats will be for 'Adsense for content', if at all they are finally implemented. They appear to be more suitable for 'Adsense for feeds'.

What is your opinion about this new ad format?