Since 1932, only one movie has won Best Picture without its director being nominated for Best Director. That was 1989's Driving Miss Daisy, and it's universally recognized as an Oscars travesty. There have been many instances of a Best Picture winner not lining up with a Best Director win (seems to happen like clockwork every five years), but only one in the modern era where the director wasn't even nominated.
In 2009, the Academy opened up the Best Picture field from five candidates to ten-ish. This meant that even if every Best Director nominee were also on the Best Picture ballot, still a solid half of the Best Picture nominees would be left out. This year, three of the favored directors were snubbed in the Best Director category -- Kathryn Bigelow, Ben Affleck, and Quentin Tarantino. Given the confluence of all these different storylines, this is a very important year for the Oscars. This is the year where they can show that categories do not overlap, and that Oscars favorites don't have to be Oscars locks.
It could happen. Argo has swept the pre-Oscars awards season, with Best Picture wins at BAFTA and the Golden Globes. Vegas lists it as a 1:7 favorite to win Best Picture. Lincoln, for reference, is second, at 5:1. That's an unbelievable lead. I can only hope that it comes to fruition.
Here are the possible outcomes, and what they mean for the future:
1) Argo wins. This justifies the Best Picture field expansion, and shows us that an IMDB page can have both Gigli and "Best Picture" on it. It gives hope to every movie that doesn't fall in the Venn Diagram overlap of Best Picture and Best Director.
2) Lincoln wins. Our worst fears are confirmed. Driving Miss Daisy was a fluke, and a one-of-a-kind fluke at that. At least five of the Best Director nominees each year are guaranteed to stay seated as the final award is announced.
3) The Master wins on an underground write-in ballot movement, showing that you don't even have to be nominated in either category to win big. I strip down to my boxers and run through Hell's Kitchen screaming ecstatically about the meaning of justice.
4) Some other film wins. To be honest, though, I think The Master has a more realistic shot of winning than some of the actual nominees.
All the other races pale in comparison to this one. In ten years, it won't matter that that chick from The Princess Diaries won an Oscar. It will matter that Argo won, firmly setting the tone for a new era in the Academy Awards.