indyank - 3:00 pm on Oct 8, 2012 (gmt 0)
There is a huge difference between showing a thumbnail linked to a website compared to just showing a thumbnail. Google is already providing the thumbnail image version of a search - it's the search results.
If you notice carefully, you would find that they do link to destinations including wikipedia towards the bottom of those answers. For example check the definitions for any English word and you will see them linking to those sites from whom they scrape.