SMS for Windows Live service is launched in United States, and UK to let you: “Update your personal message, check your Live Calendar, invite people to join your network, get contact info” on Windows Live using SMS (text messaging). No mobile browser or data plan needed – if you can send and receive text messages on your mobile phone then you should check out SMS for Windows Live. You can join by sending a SMS with a “command” to a shortcode: “For US mobile operators “ AT&T, Verizon, T-Mobile, Sprint, or Nextel” –  shortcode MyLive or 695483. And UK mobile operators “Vodafone, Orange, T-Mobile, O2, or Virgin” – shortcode 88804

More info: Windows Live Blog