An amalgamation of Did You Know and Things That Made Me Go Hmm...
All 4 winners in the major performance categories (best actor, best actress, best supporting actor and best supporting actress) were not American - actually, they're all European.
Spain's Javier Bardem won best supporting actor for his performance in No Country For Old Men. It was the first Oscar for a Spanish performer in the 80-year history of the world's premier cinema awards. British Daniel Day-Lewis won best actor in There Will Be Blood, his second win in that category. Scotland's Tilda Swinton was named best supporting actress for her role in Michael Clayton, which was quite a surprise for me, as I had Cate Blanchett as the favorite for her riveting performance in the Bob Dylan quasi-biopic, I'm Not There. Lastly, French star Marion Cotillard beat Julie Christie as best actress with her acclaimed performance as troubled chanteuse Edith Piaf in La Vie en Rose. Cotillard was the first French woman to win the award since Simone Signoret in 1960.
But this certainly isn't the first time that non-Americans have swept the acting categories. In 1964, British Rex Harrison and Julie Andrews won for best actor and actress respectively, while Sir Peter Alexander Ustinov (also Brit, although his parents were of mostly Russian and Swiss heritage) and Lila Kedrova (a Russian) won for supporting.
To quote Paul Revere, "The British are coming! The British are coming!" Although, it's been suggested that those weren't his exact words.