Update on the show's current status:
So far, despite the rumors, the show has not actually been canceled. According to producer Edward Kitsis, however, it is in danger of not being renewed due to lower viewership than Disney expected (after random and unpredictable scheduling changes, an unannounced summer hiatus, switching the timeslot to midnight, and neglecting to distribute or market the show to the worldwide, computer-savvy audience that would've happily sat through all the Hulu commercials ever to be able to stream on their own schedules and count as viewers [what, bitter? me?]). Storyboarder Eric Canete also tweeted some strong words about the company not having faith in the show (compiled here from his twitter).
Meanwhile, the petition to save TRON: Uprising and Motorcity is approaching two thousand signatures [update: now over 2200]. Tumblr fans have also started a frisbee campaign. It might not be enough, given that there are only two episodes to go; but whatever happens, TRON LIVES.