Peter Linsley, Google Image Search product manager, announced Google Images is rolling out a new feature to make the related search results more visually helpful.
In this new rollout, you will be able to hover your mouse over the related search query and see the first thing images that would show up for that related search, without actually clicking on the related image search. I don't see it yet, but here is a picture from the Google blog:
This is a nice little feature that I will find handy in the future.
Google said they are rolling it globally over the "next few weeks."
Forum discussion at Google Web Search Help.