Google is testing a new collapsible side bar where the search options and filters are after you conduct a Google search.

I reported a couple days ago on Search Engine Land via websonic.nl but now more and more people are seeing this experiment.

Here is an animated GIF to see it in action:

Here is also a video:

The Tecno-Net blog has information on how to replicate this but it means you need to install some things and run some commands. Either way, it seems Google is testing this more and more.

Forum discussion at Google Blogoscoped Forums.