It has become fairly common for games to include some sort of tutorial. Many incorporate the tutorial into actual play, as Halo and Assassin's Creed do. But there's still room to improve, of course.
One improvement would be to design a tutorial system specifically for reintroduction. Gamers often abandon a game for days or even months. They forget the controls, goals, interface, etc. It would be nice if there was an option for these gamers other than looking at a control map in the pause menu or starting over.
In most cases, a practice area would serve this purpose. Provide the player with an area where all skills may be practiced without great penalty or challenge. Allow the player to practice here without a tutorial, in case the player is able to pick it up quickly or is impatient. But also provide the option of instruction in the form of NPCs, signs, HUD pop-ups, etc.
Jogging a player's memory is different than teaching him or her new skills. There should be a different system for it, when time allows.