Recently, there was an update for xbox live which enabled users to 'rent a server'. This means that you rent a server using microsoft points and the server is under your control for the length of time that you have rented it for. It enables you to change and edit the game modes, maps and game settings and also who is allowed to join your game. You can set the settings to private (you need a particular password to enable you to join the game) or closed so nobody else can join. This enables you to play with just your friends and is the equivalent to a private match.