This is great news, if only for the fact that it's now no longer a certainty that Avatar will sweep the boards at the Academy Awards later this year.
The Oscar for best director has gone to a non-DGA winner only half-a-dozen times in the history of the ceremony, so this bodes very well for Kathryn Bigelow, though it's by no means a certainty.
The Hurt Locker (for which the director won this award) is a very good film and I'd certainly recommend a viewing of it.
A summary of the film can be found here on the IMDB.

Mark