Where we sit right now isn't pretty. @IneffectiveMath puts the Sens at 29.3% chance of making the playoffs and the Bruins at 74.8%. Sports Club Stats puts the Sens at 28.5% and the Bruins at 75.8%. Both models put the Capitals and Red Wings above 97%, and the Panthers below 1%. For those who prefer good old-fashioned points in the standings, this table should be helpful:
Washington, Detroit, and Boston each have a game remaining against each other, which may help to turn things in the Sens' favour.
Tonight's Sens game
Tampa Bay Lighting at Ottawa Senators: The Sens received some good news, in that Victor Hedman is doubtful for the game. If the Sens do make the playoffs, this could very well be a first-round preview. I don't like Ottawa's chances against the Bolts in the playoffs, but anything can happen in one game. I'm cautiously optimistic about tonight.
Tonight's other games that matter
Boston Bruins at Detroit Red Wings: The first of the aforementioned games between the BOS-DET-WSH trifecta. Who do you cheer for in this one? It depends on whose odds you like moving forward. Personally, I still think the Sens are more likely to make up three points on the Bruins than five points on the Wings. The most important thing is to cheer for not a three-point game.
Washington Capitals at Montreal Canadiens: A Habs victory has two benefits - the Caps losing ground, and an increased likelihood of the Habs winning the division.
Carolina Hurricanes at Florida Panthers: A loss for the Panthers essentially ends their chance of surpassing the Sens. I'd be perfectly fine with that happening.