Babs doesn't get mention because the team didn't clinch a spot in the playoffs until the final day of the season (for the Western Conference, anyway). That is pretty hard to overcome.
I'm surprised that Adam Oates wasn't nominated in place of Bruce. Perhaps someone was angry that there will be no Caps/Pens series. Wonder who that could be...
You're incorrect on the first point. Bruce Boudreau's 2008 Capitals made the playoffs at the very end of the season, too. As for your second point, also untrue. All voting for awards is done before the playoffs begin.
Babcock will be forever jipped out of this award. It is something commonly remarked upon by hockey commentators. Blowing away every other team in 2007-2008 didn't get it for him, and making the playoff this season despite a substantial transition and a ton of injuries didn't even get him into the top three.
It's a joke.