Menu Coding

Often an FSM (Finite State Machine) is used to control the state of the game, and to show a menu, the game is simply set to a Menu State, during which game logic is not updated, and the menu is displayed on screen. Any menu logic is handled as required, and once the menu is closed again, the game is taken out of the Menu State, and put back into a Play State, where the logic is updated again, and the game is of course, rendered to the screen.

I seem to remember there being a good article on this at Flipcode once, but I dont have a link to it anymore, perhaps you could find it yourself however.