Google is experimenting with a new look for their search page. This alternate version has an independent scroll-bar for the left-column options and features a slightly cleaner overall design.
The New Look
Google's in makeover mode for their services, obsessing over a clean and mobile-friendly version of every service. Those makeovers started with the attractive design of Google+, but has since extended to Gmail, Google Docs, and YouTube, among other services.
The search page was an inevitable step in this process, but the version we're seeing in experimental mode now may or may not be what we're looking for. It seems that the option featuring multiple scroll bars is going through internal testing. Here's a video taken by Tech-Net:
This was confirmed as an official experiment by Search Engine Roundtable.
Those interested in checking the experiment for themselves may be able to do so through modifying their cookies. The instructions provided by Google Operating System, however, seem to have stopped working shortly after the original post was made.
The idea of multiple scroll-bars is an obvious attempt to keep things clean while expanding the options in the left-hand column. Feedback from those who have tried the experiment has been mixed.
Other recent Google search page experiments have included infinite scrolling and a locked search box. The only addition that's made it into standard use, however, has been the black toolbar at the top, which is now common throughout Google's products.