The deal is reportedly a two-way deal and if he clears waivers he will be re-assigned to Wilkes-Barre/Scranton Wednesday.
Kostopoulos, 34, was selected by Pittsburgh in the seventh round (204th overall) back in the 1999 NHL Entry Draft. Throughout his NHL career, Kostopoulos has amassed 156 points (60G, 96A) in 615 contests for the Penguins, Kings, Canadiens, Hurricanes and Flames.
This season Kostopoulos has been playing in WBS on a PTO (professional tryout contract), and in 17 contests he has recorded seven points (3G, 4A).
Achieving a rare honor last Friday, Kostopoulos became the first player in WBS history to register 100 regular-season goals.
The Pens also have announced that they have recalled forward Beau Bennett from his brief stay with WBS.
Since Boychuk cleared waivers noon today and was just claimed by the Nashville Predators, the Pens almost immediately called Bennett back up to fill the empty roster spot.
In eight games this year for the Pens, Bennett has recorded three points (1G, 2A) and a plus-1 rating.