When I worked for a consultant to Microsoft in the early 2000s, they were excited about the powerful search features they were planning to deliver in Longhorn. But Apple beat them to market with Spotlight, and to my knowledge, search has never turned into a differentiating feature for Windows.
It's kind of crazy to think back to those conversations with Microsoft about their long-range plans. Some they have delivered well, like the transition to a subscription model for client applications. Some they have not, like native peer-to-peer social networking in the OS.