The blog post entitled Released: Contacts API, Windows Live Data Protocols on the Windows Live Dev blog states

Today we have a few more things for you, starting with this . . .

To date, access to Windows Live Contacts has been exclusively through our Contacts Control, but now we also offer an API for Contacts as well. The Windows Live Contacts API is a RESTful API that works on Address Book objects. The Contacts API offers a more granular control over the user experience than the control, and allows users to grant and revoke permission to their data on a site-by-site basis. Windows Live Data provides the protocols to manage the permissioning process.

Try them out and let us know what you think in our forum.

The Windows Live Data service provides a framework for applications to request and receive access to a user's data stored in Windows Live. An overview of the process is available in the documentation on Requesting Permission to Access Users' Windows Live Data.

The Windows Live Contacts API is a RESTful Web service created by my team for accessing a user's Hotmail contacts. How we use HTTP verbs is described in the documentation Getting Started with Windows Live Contacts API. You'll probably catch me talking about my contributions to future versions of the API in coming months.