Google started to integrate in the search results information about the scientific papers included in Google Scholar. Below the snippet, Google lists the authors, the number of citations and links to related articles and other versions available online. The integration is not perfect and the search results look cluttered, but it's yet another class of results that have richer snippets.
Here's the top search result for buddy tree (a data structure):
... and the same result at Google Scholar:
Google also shows additional information next to videos, books, web pages that include addresses and tests displaying metadata for forums and extracting specialized information from web pages. While Yahoo tries to convince webmasters to make structured data explicitly available, Google has a more practical approach and uses what's already available to enhance search results.
{ via Blogoscoped Forum }