What the hell do you mean no spoilers? If a mod could edit a *SPOILERS* into the title that'd be leet.
*SPOILERS******
Yeah I thought they'd be alluding to Jack Bauer killing himself by jumping. The silent clock is usually only used for things like deaths of major characters; of course, it could have been signaling Jack's ultimate resolve to leave his attachment to Audrey behind.
And of course, there's gonna be another season. 24 without Jack Bauer is like BF2 without bugs and glitches and hackers.
****END SPOILERS****