It only seems to be a test at this stage as it only shows for me in Firefox 3 and not in Internet Explorer 8. A colleague of mine cannot see the change at all in either browser. Take a look at the two screenshots below (click on the image for a full size version).
The first is from IE8 and shows a typical layout. I’m using a 24″ monitor with a resolution of 1920×1200 and the browser maximised. Notice the massive space between the organic listings and the PPC ads to the right hand side. The ads are unlikely to catch anyone’s eye in this position.
This second image is from Firefox 3, showing the new layout. If I enlarge the browser window the PPC ads stay snugly up against the organic listings and are much more likely to catch the eye of someone browsing.
I’m surprised this new layout hasn’t already been tested and brought into full use. It doesn’t make sense to have all that white space and banish the pay per click ads to the far right hand side of the screen. Yahoo is actually worse in this respect, with even more horizontal white space, while Bing has been leading since its launch with their ads hugging the organic results tightly (see the following two screenshots).
If Google make the change permanent, it will be particularly welcomed by anyone involved in PPC management as it will naturally increase the likelihood of someone clicking on one of their ads.