Google has updated their Sitelinks. Google Sitelinks were previously comprehended as Web Categories. Google has explained Sitelinks in their Webmaster help center.

The links shown below some sites in our search results, called Sitelinks, are meant to help users navigate your site. Our systems analyze the link structure of your site to find shortcuts that will save users time and allow them to quickly find the information they're looking for.

Now it is clear that Google updated them and gave some more sites sitelinks.

Search Engine Roundtable has a good post on it.