In October, I reported a very similar look at Search Engine Land where Google was testing a colored top bar navigation look.
Now some more users are seeing a flavor of it, as reported at the Google Blogoscoped Forums.
Here is a new picture this person shared:
Focus your attention to the top bar and you will see the slight difference.
Nothing major, but we like to cover even the smallest changes at Google.
Forum discussion at Google Blogoscoped Forums.