With the results of tonight's games (Montreal winning, Boston losing) things are a little clearer.
If the Penguins beat Philadelphia tomorrow in regulation, Pittsburgh will be the #1 seed (more wins than Montreal) and take on the 8th seeded Flyers.
If Pittsburgh beats Philly tomorrow in overtime, the Flyers are still the #8 seed (Ottawa has more wins and Boston took 6 out of 8 points from Philly).
If the Pens lose tomorrow, they'll be the #2 seed in the East and draw Ottawa (edit: fixed).
Philadelphia, by virtue of their win, would jump up to the 6 slot and face Washington.
Expect this to be a tough and intense game. Philadelphia doesn't want to have a seven game series with Pittsburgh, I think they'd rather take their chances with an untested Caps team that has had to expend a lot of energy just to make it to the playoffs.
Ottawa or Philadelphia, either way we'll know the Pens immediate playoff plans by 3 PM.