From Angus Logan, the Windows Live blog:

We believe that you should be able to choose to take your Windows Live data with you when you travel the web. Messenger Connect allows you to do that by providing a way to sign in to third party web and client applications using your Windows Live ID. Messenger Connect allows you to bring your Windows Live profile and contacts with you; easily share with your friends and enable Windows Live Messenger-based chat within third party applications; and access your photos, calendar, and more.

In order to enable third party applications to ‘connect' and interact with Windows Live accounts, we needed to design to help to ensure that customers' data is protected and accessed in a manner consistent with customers' expectations and desires, as well as enable great partner experiences.

Owning your data. Interesting concept.