In her prepared remarks during last week's quarterly earnings call, Yahoo! President Sue Decker said the following:
Although we haven’t elaborated on this much publicly, on the back end we have made a major investment in open source development of grid computing which provides a substantially greater scalability at fast iteration on core technologies. This is already dramatically impacting our competitiveness in algorithmic search and advertising.
For example, in some cases we have an order of magnitude 10x improvement in indexing speed. This has been a multi-year project and we’re on track to have our future Search and advertising systems built on the new infrastructure, positioning us well for acceleration in iteration and experiments that are likely to lead to significant future product enhancements.
In other words, we're using Hadoop more and more internally to dramatically improve some of our operations. We'll be talking a lot more about that in the coming weeks, along with introducing some key members of the grid team here at Yahoo!