tedster - 3:42 pm on May 7, 2011 (gmt 0)

Here's a story from TechCrunch about the test:

...it's great that Google appears to be trying to clean up the look of the results page, which has gotten pretty cluttered over the years as they add more and more types of information and snippets. But the new design is too sparse. And the colors are too soft. It looks like Bing on a bad day. The weirdest thing about the test is that it actually gives you much less information on the screen. This will require users to do more scrolling and paging through results to find what they're looking for. Google Appears To Be Testing A Sparse, Ugly New Results Page [techcrunch.com]

From the screenshots in this thread, it looks like multivariate testing with more than two approaches in play.