"If we detect that your query has 'high image intent' (meaning, we're pretty sure you're looking for images) we'll start showing more images on the page. If you add words like 'photos', 'pictures', and 'images' to a query, that means you're probably not looking for a blog post or video. Showing more images on the main search results page makes it just that much faster to find the image you're looking for," informs Google.
Another change is that Google will show a larger thumbnail when you mouse an image from the OneBox, just like in Google Image Search. The OneBox result now looks like the first page of images search results, but it's interesting to notice that the ranking is slightly different.