I have to echo some others with my feelings that Iginla is definitely not the player he once was. In fact, all of the players the Penguins have picked up recently are well over the hill, but adding them to an already strong team will likely bring the best out of whatever these guys have left. Even if they are all rentals, they will give every ounce of what they have now that they are on a Cup favorite team, plus they will all likely be partnered with stronger linemates than they had with their respective former teams. I don't know much about the prospects involved in these trades but from what I've heard, the Penguins still have their 3 best guys. They gave up some picks, which definitely hurts them in the future, but these look like some solid moves by Shero.
Only concern for Pitt is that you never really know how moves like this will affect the team chemistry. They are already on a huge win streak. Adding this many new people in such a short time could mess things up, at least in the short term.