Xbox Live will be getting three major updates this fall, designed to make the online experience for Xbox users more connected. The updates are: Clubs, Looking For Group, and Arena.
Clubs are sort of like guilds hosted on Xbox Live. If you've got a particular group of players you regularly hang with, Clubs will give you a dedicated space to organize, coordinate, and chat. Looking For Group is pretty much what it sounds like - a service that lets you advertise yourself as you try to complete various challenges. Want to take on that new Destiny raid? Looking For Group is where you wanna go.
Lastly, Arena is a space dedicated for professional-level players. You'll be able to register, view, and compete in tournaments set up by various publishers. One of Microsoft's first partners will be EA, so Battlefront and Battlefield players, I'd suggest you get warmed up.