Its very true that you learn something new every day and today I learned that Yahoo are using Nutch in a research capacity.
Welcome to the Yahoo! Research Labs implementation of the Nutch open source search engine (www.nutch.org). This search engine is intended as a demonstration platform for a number of search related technologies
I found it purely by chance. If you don’t believe then have a look at Yahoo’s intall of Nutch. I think that its a smart move on their part because they get to see how it does its stuff and assess it. They may even be able to incorporate some of it into their own products.