From their site: The Windows Live ID Client 1.0 SDK provides a managed API for Windows Live sign-in authentication. Included in the release is a sample application with its source code, so that you can build your own client applications. he Windows Live ID service uses the same functionality as Messenger to cache the user name and/or password for use in subsequent user sign ins. Gain hundreds of millions of potential users of your application.
The following is a list of SDKs from our SDK directory that matched your search term. Though your definition of an SDK may differ, in our world, we define SDKs as platform- specific tools for consuming existing APIs of the sort we list in our API directory. For example, the Ruby SDK for consuming the Twitter Ads API. If you think an SDK, API, or other asset is missing from our directory, be sure to check our guidelines for making contributions to ProgrammableWeb.