Title: CAPTAIN AMERICA#347 by Mark Gruenwald (writer) and Kieron Dwyer (art)
The 1950s Communist Red Skull is broken out of prison. He gets into a helicopter and is flown off. The pilot literally shoots him out of the helicopter and declares, "Justice is Served". Shortly thereafter he calls up a mysteryman villain to tell him what happened, which causes the mysteryman to laugh in delight
Is it a key part of the overall Scourge storyline?
Yes. It shows that the Scourge operation is back in business. It also begins a lengthy red herring.
Does it tie into the main story in this issue?
Yes. The mysteryman, whose identity is revealed in this Scourge's next appearance, #350 (see my next review) has been behind the scenes regarding many of Captain America's problems in recent years (at the time this story takes place)
The Scourge seen here has not been seen previously. See my review of #3550 for the reason why he isn't the same person from #320