Microsoft is planning a big release in coming months including Windows Live Writer 2010 and Windows Messenger 2010. After the release of Microsoft Office 2010, it is expected that the Live Writer 2010 will have some features from that. And about the messenger 2010, it is visible in the first look that they are highlighting the social media like Twitter integration really well.
Here is the first look of Windows Live Writer 2010 and Windows Messenger 2010,
Windows Live Writer 2010
Windows Messenger 2010