It’s a very smart move (and one that will be sure to make John Dvorak happy). As a business traveller for the past 3 years, it’s always driven me crazy that the airlines wouldn’t let you use your phone or Crackberry after touching down. On the flights I’ve taken, many folks simply ignored the rule and just spoke quietly enough so the flight attendants wouldn’t hear them or simply listened to voicemail without calling people back.
I hope Southwest follows suit.