Rogers explained that Party will give players cross-game chat capabilities, allowing them to invite friends to groups and launch games directly through the UI, which all party members will be invited to. The LiveArea is a tad more esoteric: it will display information about software as it is launched, and will allow users to "comment on people's activities within the game as well as publish your messages." Sounds like the perfect receptacle for smack talk.
Finally, the Activity feed will show the in-game accomplishments of friends (including high scores and Trophy unlocks) in real time. The feed can also be updated by publishers and developers, though Rogers suggested, "it's important not to spam users too much and to use it sensibly." We pray that Rogers' advice is heeded.