The Web is moving from a static, one-to-many model to a participatory, user-centric model, based on user-generated content, social networks and two-way conversations. To get there, we’ll need a combination of technology, patterns and practices—all coming together to form a Participation Platform. Today Yahoo! provides a broad spectrum of services to fulfill the promise of the Participation Platform, enabling third-parties to incorporate Yahoo! content and services in web sites and software applications. We’ll look at Yahoo! as a web services platform for developers and show off some new and emerging services that will transform the platform in the future.