Luke Skywalker, that guy from that one movie, will make an appearance in Force Unleashed via Downloadable Content, according to Wired (who, in turn, credit IGN). There will be two packs of DLC, one that features classic characters like Luke and Obi Wan Kenobi; the other one will add one new mission to the game.
Does this mean that Luke has travelled back in time, slept with some woman who then gave birth to Darth Vader, thus making Darth Vader and Luke have a hell of a weird father-son relationship? Did I just totally spoil Empire Strikes Back for you? And did I just totally rip-off Futurama? The answer: probably revealed along with the release dates and price tags for this extra content.
Source: Wired