Windows Live Messenger SDK

Microsoft has announced a software development kit (SDK) for Windows Live Messenger:

Let web site visitors interact with Windows Live Messenger users using the Windows Live Messenger Library, Windows Live Messenger IM Control, and the Windows Live Presence API.  You can also use the Windows Live Messenger client, version 7.0 and later, to develop a single-user or multi-user application through the Windows Live Messenger Activity API.

According to Microsoft the software development kit provides:

1. IM Control - The IM Control enables web sites to show the presence of Windows Live Messenger users and let site visitors engage in IM conversations with site owners or representatives.
2. Presence API - The Presence API is an HTTP-based API that returns a Windows Live Messenger user's presence.
3. Messenger Library - The Windows Live Messenger Library is a client-side JavaScript library that enables third-party sites to seamlessly add instant messaging capabilities with Windows Live Messenger.