We've covered many Google user interface tests and we've seen the bigger Google fonts in the search results, we've seen Google test not displaying underlines and much more. But it seems Google have ramped up those tests.
I covered it at Search Engine Land earlier this week but more and more people are discussing it online.
Here is what it looks like side by side, the left is the new interface and the right is the old (click to enlarge):
Now, there are complaints because there are CSS and formatting issues with this new design, new test. Yes, it is a test and thus it is allowed to have mistakes.
A Google Web Search Help thread has one searcher seeing the bugs and he has no clue he is in a test, he just is a searcher trying to find search results. But the text is overlapping for him and makes the search experience poor. Again, he has no idea he is in a test.
David Naylor covered many fails with this test as well.
Either Google is going to kill the test and not launch it or they will fix the issues and eventually launch it. It seems Google stepped up the testing on this design this week but it doesn't mean it is going live.
I am personally able to see it randomly as well, so it is being heavily tested.
Forum discussion at Google Web Search Help.