Google always is testing and here is a bolder font for the search result snippet URLs. Andrea Cruz spotted this test and posted a screen shot on Twitter.
You can see when you compare the normal snippet URL font to the one she spotted, the test is a bolder font type for the URL.
Here is a screen shot of the test (click to enlarge):
Here is a screen shot of the normal result (click to enlarge):
So let’s add this to the list of the many Google UI tests we’ve covered.
Forum discussion at Twitter.