The Messenger Web Bar shipped with the recent release of the Windows Live Messenger Web Toolkit, provides a very usable default instant messaging experience for web sites – it includes a contact list, a profile area, and support for displaying ongoing conversations. It is meant to augment and not distract the user from your web site,” Gordon stated. “Since the Web Bar and all of the UI Controls are constructed using HTML and CSS, web sites have complete control over how the controls appear to the user. With this flexibility, there is a wide range of customizations that a web site can do, ranging from simply changing the font color, to providing a completely custom experience.
Source:→ MSDN Blog