Windows Live Messenger IM Control

Windows Live Messenger IM Control is a service provided by Microsoft as part of its Windows Live services which enables websites or blogs to show the presence of Windows Live Messenger users, and let site visitors engage in instant messaging conversations with the Messenger users. A website can invite its users to share their Messenger presence and exchange messages with visitors to the site. When a site hosts the Windows Live Messenger IM Control, site visitors can instant message Messenger users directly from the browser without installing the Windows Live Messenger desktop client on their computers. The IM Control is supported in Internet Explorer 6 or 7, and Firefox 2.0 on Windows and Firefox 2.0 on Mac OS. The IM Control is supported in 32 languages.

Windows Live Presence API
Windows Live Presence API is an HTTP-based API that returns a Windows Live Messenger user's presence using JavaScript Object Notation (JSON) or an image. The Windows Live Presence API can be used in conjunction with the Windows Live Messenger IM Control. A Web site can show a user’s presence using the Windows Live Presence API and let visitors send messages to the user with the Windows Live Messenger IM Control.