I was able to see the new option by adding &gl=us to a search URL, so it's likely that Google still tests it. The suggestions for image search are different than the ones usually displayed in a list of related searches at the bottom of a search results page. People usually want to find Nike's logo and only search for [Nike], want to see Greece's map and only search for [Greece] or only enter [1984] to find the cover of George Orwell's famous book, so a hint to try to a more precise query is helpful.
The feature is already available at Yahoo Image Search, where you'll also find a box of recommended searches at the bottom of the page: "others who searched for ... also searched for". Live Search shows a list of related people when you search for a famous person, like Natalie Portman.
The top queries in an image search engine are usually celebrity names. What other things do you try to find using these specialized search engines and what improvements would you like to see in the future?
Related:
Tips for Google Image Search