The previously mandated analog TV cutoff date of 2009 has just been extended by the FCC, meaning that even though broadcasters (the people like NBC who send out the shows) will be dropping the analog feed, cable operators (the local cable companies that take your money every month) will still have to support old ass analog TV sets. They have two ways do to it.
The cable operators, come Feb 2009, can either convert digital SD signals to analog SD signals and throw it across their cable lines to you, or they can give all their grandma and grandpa customers with old sets a digital to analog converter box. It's a tradeoff between sucking up more of their bandwidth or giving away free equipment.
Come 2012, five years from now, the FCC will make another decision whether to force cable operators to support analog signals. [Ars Technica]