Google is testing showing image thumbnails in the mobile search results again. They did this back in December 2014, and we know Google is constantly testing user interfaces, so this should come as no surprise.
Dan Smullen shared a screen shot with us on Twitter showing this off. We can personally not replicate this, but here is that screen shot:
We have emailed Google for a comment about this, but we suspect it will be the line about Google constantly testing and experimenting with new features, layouts and designs.