A few days back I posted about Live Contacts, the new service that was released in beta form alongside Spaces 10.5. One thing I didn't mention though was its integration with existing Windows Live services.
To recap, Live Contacts allows you to publish personal and business information to specified contacts, and if they subscribe to it they will automatically see any changes you make. Outside of Spaces Live Contacts can already be found (with limited presence so far) in two Windows Live products, Mail and Messenger.
Assuming you have already subscribed to someone's Live Contact information, the back of their Messenger contact card will show the information they have published. If they have specified an address a link will appear on the contact card that when clicked will load a Live Local map at this location. Now you don't have to look stupid and ask to be reminded where someone on your contact list lives. Additionally, all phone numbers are hyperlinks that when clicked will launch Windows Live Call.
Mail integration is slightly less advanced at the moment, showing only the information you have subscribed to. However as with Live Contact integration in Messenger, you can expect this to develop as the product moves towards v1.