Microsoft's Danny Thorpe talks about the new version of the Windows Live Contacts Control adds a new "tile" view that displays the photos of your Windows Live IM contacts in the control, and makes starting an IM session with them a simple one-click operation. The top part of this screenshot shows the new tile view. The bottom part is another instance of the contacts control in list view mode.
The web site that is hosting the contacts control can set a message string and/or URL that will be preloaded into the IM chat window. This makes it very easy to build a web site that encourage visitors to bring their friends to your site - the "swarm" effect that ad-monetized sites crave. Viral swarming, even.