Windows Live Messenger has an array of extensibility points for partners to plug into, and for users to take advantage of, including:
Embedding Messenger in your website – Web Messenger Toolkit lets users chat within context of another site, so you can watch TV shows together or chat about restaurant reviews as you look at them together. Site developers can integrate with WLM Web Toolkit in three easy ways, using simple interactive SDK with code samples, etc.
Contact import/export lets you easily pull in contacts from major email & social sites around the world, to invite friends to Messenger, and vice versa to bring your Messenger contacts with you to sites & services you choose. You can easily bring contacts into Messenger and other Live services from Facebook, MySpace, LinkedIn, Gmail, AOL, Hyves, and more. For partners who want to let their users bring their Messenger contacts into their site, an open, RESTful set of APIs and an interactive SDK are available.
Web activities and social feeds let users automatically share what they’re doing across the web with their Messenger friends, where users can choose to automatically share what they’re doing on 75 partner sites from around the world. As part of this program, we support and are co-authors of the activitystrea.ms standard for activity feed ingestion.