Snopes says:
Origins: Although there once was some truth to the item quoted above, the information it contains is long outdated and never had anything to do with Pepsi or Coca-Cola. Neither soda company is producing, or has ever produced, redesigned cans bearing any portion of the Pledge of Allegiance or an image of the Empire State Building. This issue concerns a special patriotic can design produced by Dr Pepper back in November 2001, a can which was marketed for a limited time and has been off of store shelves for three years now (since February 2002).
The brouhaha began in mid-November 2001, when the Dr Pepper soft drink company, in response to the terrorist attacks on America a few months earlier, introduced a new can design featuring the Statue of Liberty with the words "ONE NATION . . . INDIVISIBLE" from the Pledge of Allegiance displayed above it:
http://www.snopes.com/politics/business/undergod.asp