As Rod says, the ad would have been slightly easier to laugh at fifty years ago, but I can't say I find it all that offensive even now. And as a fan of counterfactual histories and peculiar maps, I think it's too bad that Absolut is apologizing instead of kicking off a series, each targeted to a particular country's most implausible irredentist fantasies. For the Francophone Canadian market, you could have had Absolut Quebec, showing a vast "Republique de Nouvelle France" extending south to the Caribbean while Les Etats-Unis clings to the eastern seaboard. Then of course there would be the ad in the British tabloids depicting the United Kingdom of Great Britain and North America (governed, one would hope, by the House of Stuart); the Parisian billboard showing the French Empire sprawling to its Napoleonic boundaries; the two-page spread in the Athens papers showing a Greece with the boundaries of Justinian's Byzantium; and the micro-targeted, Venice-only campaign depicting La Serenissima restored to its former glory. Meanwhile, the campaigns for the Muslim world could be outsourced to the advertising firm of Bin Laden and Zawihiri - I hear they have some ideas on that front.
Having just crossed the fine line separating "joking about implausible irredentisms" from "joking about implausible irredentisms that still inspire mass murder," I'll go re-read Jerry Z. Muller's fine essay on "the enduring power of ethnic nationalism" as penance. But some enterprising parody artist should pick up where I left off, since the revisions of the Absolut ad for the "America's Enemies" market - a Middle East without Israel, a Russian bear devouring the former Soviet Union, a Greater Venezuela - more or less write themselves.