Anyone can build a Windows Live Messenger client—with open standards access...

We’ve previously talked about the principles that guide us as we strive to continue delivering the most convenient ways to chat with the people who matter the most to you. Today we’re taking another step, with the public availability of access to the Messenger network via XMPP, an open standard. This means that anyone can build innovative messaging clients—either stand-alone or built into their devices—that include access to Messenger’s 300 million active users.

Read More at Microsoft Windows Team Blog