Over a year ago, Google was caught testing roboto font in the search results snippets. Well, now Ruben Gomez spotted Google running that test again and posted that screen shot on Twitter.
Here is the roboto font in Google's search results:
The Roboto Font was created by Google's Christian Robertson and revealed at Google I/O in 2013. It may be that Google want to switch to this font, because it is pretty crisp and clear.
Forum discussion at Twitter.