Tom Warren has the scoop on the next version of Microsoft's instant messaging client, which will ship sometime in 2010 as part of Windows Live Wave 4.
The main Messenger window that contains your contacts has changed somewhat. Included on the left hand side is a "social stream" of updates provided by Windows Live. These are updates from your Messenger contacts and the data is provided by Windows Live. In current public Messenger builds some of this integration is present at the top of a conversation window. Windows Live Messenger aims to add to this by using the "social stream" as a showcase for your contacts updates. Providing your friends have including their Facebook, Twitter and Blog posts into Windows Live then you will see this in the stream.
One of the main improvements for Windows Live Messenger 2010 is the introduction of tabbed messenger conversations ... Windows Live Writer Wave 4 has also been improved with the introduction of the ribbon interface seen in most other Windows Live applications.
Looks interesting, though I'd love to see the Windows Live guys really go for it and do the full-blown WPF interface. You never know.