The eagle-eyed Sergey Alakov spotted Google testing a taller, more spacious, Google mobile search results user interface. There is simple more vertical space between the search results. He posted this on Twitter and said "Google testing larger spaces between search snippets."
Here is a side by side comparison so you can see yourself:
This isn't really a big deal, but might make some folks thumbs tired with more scrolling. :)
Forum discussion at Twitter.