It was initially believed that Iginla was going to the Boston Bruins in exchange for prospects Matt Bartkowski and Alexander Khokhlachev, and a conditional first-round draft pick.
The Penguins and Bruins went down to the wire in their attempt to acquire Iginla, but at the end, the Penguins won out.
"The final decision was made this evening," said Flames GM Jay Feaster. "Ultimately it all came together during the game tonight."
In 31 games with the Flames this season, Iginla has registered nine goals and 13 assists for 22 points.
Draft 11th overall by the Dallas Stars in 1995, Iginla was traded to the Flames with Corey Millen on Dec. 19, 1995 in exchange for Joe Nieuwendyk.
In over 15 seasons with the Flames, the seven-time All-Star has accumulated 525 goals and 570 assists for 1,095 points in 1,219 NHL regular-season games. He's also tallied 831 penalty minutes.
Iginla, a two-time 50-goal scorer (2007-08; 2001-02), entered this season having reached the 30-goal mark in 11 straight seasons dating back to 2000-01. His best season came in 2007-08 when he recorded a career-best 98 points (50 goals, 48 assists) in 82 games with Calgary.
Agostino, 20, was drafted by the Penguins in the fifth-round (140th overall) of the 2010 NHL Entry Draft.
In 33 games with Yale University this season, Agostino registered 15 goals and 22 assists for 37 points.
Hanowski, 22, was drafted by the Penguins in the third-round (63rd overall) of the 2009 NHL Entry Draft.
In 34 games with St. Cloud State University, Hanowski registered 16 goals and 13 assists for 29 points this season.