It looks like Microsoft is going to be releasing two dashboard updates this year. The first is the summer update (detailed
at CVG) which includes the Netflix update, Avatar updates, games on demand, and a bevy of other features that will be released to everyone on August 11th.
The second update (which is "coming soon") is the big one that will include Twitter and Facebook integration along with custom radio stations from Last .FM and instant 1080p streaming. It's a bit interesting that Microsoft is going with two updates this year (especially so close together) after going with the one big release last year (although it was the semi-game changing NXE release).