Google seems to be testing a web search feature for the image pack that keeps you within web search when you click on a specific image. Punit shared a screenshot the other day (not on April Fools) of how Google placed the larger image preview on the right of the web search image pack results.
Here share this photo on Twitter (click to enlarge):
I tried dozens of browsers and I was unable to replicate this but I do kind of like how this shows you more details of the image without taking you directly into Google Image Search. So Google is keeping you on the web results page and not moving you over to Google Images.
Forum discussion at Twitter.
