If you or someone you know belong to that 3 million-plus group, make sure to take advantage of the free coupons being handed out at DTV2009.gov (888-DTV-2009 if you prefer to call). Each household is eligible for two $40 coupons, which must be used to purchase a TV converter box. The DTV2009 site also notes that a mobile assistance tour has been scheduled to aid with the transition. Presently visiting over 20 U.S. markets, the tour staff is equipped to demonstrate converter box hook-ups.
If you use cable or a satellite based provider, you are obviously unaffected by the change. Time to get rid of those rooftop antennas, or at least upgrade them.