It's part of the deepening relationship between Google and Wikipedia. Google is using Wikipedia content to flesh out its search results, in exchange for access to the free work of thousands of unpaid volunteers. Sergey Brin's recent $500,000 donation to Wikipedia seems like a bargain compared to other costs of data collection.
It's yet another reason why you should stop giving Wikipedia money http://newslines.org/blog/stop-giving-wikipedia-money/