Thanks to Major Nelson for this update :
We’ve just released the latest new features for your Xbox 360. In case you’ve been off the grid for the past few months and don’t know what is in this update, allow me to give you the some of the highlights: Facebook, Zune Video, Twitter and Last.FM. Here is how to find ’em: Facebook and Twitter will appear automatically on your dashboard in the new My Community channel, Zune Video is in the Video Channel and Last.FM will be found under the Music Channel.
Assuming you have the latest Xbox 360 system update from Xbox LIVE, these new features will automatically appear sometime over the next few hours. Availability of these features will vary by region.
Enjoy the new Xbox Dashboard experience, I’ve had it for the past 2 weeks and it’s brilliant. Enjoy.