Google has been testing with a new design for its search page results, in that they added the underline on links, increases the font size, and gets rid of the colored boxes around ads in favor of a more organic look.
Google regularly does these tests, and many of them never see the light of day in terms of a broad roll-out. This one, however, is launching to everyone now.
Googler Jon Wiley made the announcement on Google+:
Here is the look: