Lately, Google is experimenting more than Sheldon Cooper on their homepage - and now, also on their search results.
They're testing a permanent left sidebar in their search results, which would turn the results into three columns: new sidebar, organic results, search ads. Hmm, this reminds us of Bing. And Bing reminded us of Ask's 3D design (which they've since abandoned).
Additionally, after experimenting with removing the submit buttons on the homepage, now Google is bringing back the buttons and testing them with a new color: bright, primary blue.
In the Google help forums, two screenshots of these experiments were posted:
Blue Buttons on Homepage