Besides just looking a lot snazzier, the New Xbox Experience uses a whole new foundation that's server-based rather than sitting on your hard drive, so it's easy for Microsoft to add on features and apps. One possibility is basically movie parties—you and your friends could all watch Indiana Jones on Netflix at the same time—or more likely, photo sharing.
All Microsoft has to do is "build that app, drop it in, party enable it and we’re good to go" says Xbox senior strategist Rob Gruhl. So while the movie party feature isn't specifically planned on, since "those types of things are certainly the aspiration," according to Xbox marketing head Albert Penello and they've discussed photo sharing, it looks like we can definitely expect to see some social app action like that in the future.