I've seen a lot of comments about this, and I'm a bit weary of everyone's obsession with Kathryn Bigelow's gender, too. But it's a significant milestone nonetheless.
The directors branch of the Academy is notorious for being a boys club. Not just because it only awarded men up until last night, but because it's members are this small, exclusive, tight group made up entirely of men. The directing Oscar is Hollywood's thickest glass ceiling, and to see it shatter last night was a HUGE deal. To illustrate, lemme tell you a little story about the woman who handed Bigelow that Oscar last night (and hilariously asked if she could keep it), Barbra Streisand.
Say what you want about Babs, an honest look at her career as a director (even the amazingly self-obsessed The Mirror Has Two Faces) shows that she has a true gift in that arena, regardless of her sex. When she made her first film, Yentl, she showed it to Steven Spielberg. The media would later distort this exchange into Spielberg giving her "advice" (a distortion that led to her refusal to give interviews for a decade), but the only advice he gave her was, and I quote, "Don't change a frame." Streisand would go on to WIN the Golden Globe for Best Director for this film, but when Oscar nominations were announced, her name was noticably absent in the directing category. In 1991, she directed The Prince of Tides, which went on be nominated for 7 Oscars, including Best Picture. Streisand was also nominated for the Directors Guild award for that film. Yet she was shut out again for the Directing Oscar (Billy Crystal ribbed the Academy for this in his opening number - "Did this film direct itself?!").
L to R - Lina Wertmueller, Jane Campion, Sofia Coppola
There has been a decided gender bias in Hollywood, and not just at the Oscars. Women filmmakers are consistently ignored, not just for awards, but by the studios and media as well. Where once upon a time 25% of screenwriters were women (writing ultimately half of the films that were actually produced), now it's more like 6-7%. It is the fondest hope of mine - and I mean this seriously, as a woman who hopes to break into the movie business - that Bigelow's win will draw more attention to female filmmakers. I'm not saying give them awards and movie deals just because - quality should always trump gender politics - but don't keep ignoring them, because they're not going to go away.