That news comes via a Microsoft press release, which also talks a bit about what'll be in said update. The features have all been previously announced, including the ability to get friends together for group-based Netflix streaming, a feature that I don't quite think I understand yet. When I'm watching movies, I generally want everyone to shut the hell up. Wearing a headset so I can hear a group of people prattle on while I watch something only makes sense if we're watching something that's completely awful... oh. OK, yeah, now I get it. There's some truly awful stuff in the Netflix streaming library, so this makes perfect sense.
The Games on Demand service that lets you purchase digital versions of Xbox 360 games will be part of the update, and Mass Effect is expected to be among the first releases, along with BioShock, Assassin's Creed, Lego Star Wars: The Complete Saga, and Sonic the Hedgehog. Over 30 games will be available on the 11th.
The marketplace for premium avatar clothing and props will also launch on the 11th, letting you "purchase branded apparel from your favorite fashion labels and Xbox 360 games." Do you think you'll spend money on any virtual gear for your dashboard dude? I've always felt that clothing companies needed to work something out where I could buy clothes in a store and get a download code so my avatar could wear the same article of clothing. Or, alternately, let me preview clothing on my avatar and when I buy it there, send the real-world clothing to me at home. Other than the process of actually creating the digital versions of an entire clothing line, that sort of physical/digital clothing thing seems way more exciting to me than "hey, you could buy a Halo helmet."
Of course, this won't be the full roll out for all the announced dashboard features. Support for Twitter, Facebook, and Last.fm is still in the works along with the video marketplace overhaul that'll allow for 1080p streaming. All of that is pegged for release this Fall.