Chris Ainsworth posted a screen shot of a Google user interface test in the Google search results on his Google+ page. He noticed a subtle change for the sitelinks for branded search results. Specifically, a border around the search result with the sitelinks.

I personally cannot replicate it but here is a screen shot from Chris.

Google Sitelinks With Borders:

Google Sitelinks Without Borders (As I See It):

Again, this is a pretty small change but it does really make this search result look dominant.

Forum discussion at Google+.