Along the past few months Google seems to have been very productive about testing visual improvement while returning their SERPs: Underlined links, breadcrumbs, snippets …
Google team is always at work, but the question is, how this visual result improvement can really change something? And how do they really track the results of their tests if they change so often the stuff proposed?
There are many different opinions on this topic, and I was talking about a particular aspect just last week with Everfluxx, commenting on his blog.
Everfluxx strongly believe that visual changes have an impact on the CTR, because some pixels of extra space or a missed underline can make the difference while clicking. I instead believe that Google's users are so savvy to click everything they can if a proposed results is enough interesting, and so the most important difference on the SERP results is again played by webmasters and from the content and page title they create.
Beside this, it's very interesting the latest changes on which Google is currently working: the snippets. On its blog, Google team point out the difference on how a good internal link (on page) strategy play a very interesting factor to help search engine algorithm to collect information to propose the snippet.
The post explains pretty well how to go through and I think it will be a worth have a read.