From Newsarama:
Also in Fox's announcements - 24 will return Sunday and Monday, January 11th and 12th for two, consecutive two-hour engagements. The two-hour prequel movie 24: Redemption setting up the new season, and starring Jon Voight as the antagonist for the season will air on Fox Sunday, November 23rd.
The new season of 24 will open with the CTU (Counter Terrorism Unit) shut down and dismantled and Jack Bauer (Kiefer Sutherland) on trial. Carlos Bernard, who plays Tony Almeida, returns to the series, though he was presumed dead.
The debut in January will mark the first time new 24 episodes have been aired in nearly two years. Filming on the new season was shut down late last year due to the Writer's Strike, which led Fox to hold the season back until midseason 2008-2009. Work stopped on the season this past September due to quality-control issues with scripts.