The Penguins have claimed Chris Thorburn off of waivers from the Buffalo Sabres.
Thorburn is a right-handed center. This would most likely be the primary reason for the Pens claiming him. He's also still young (only 23) and had a decent year in the minors last year, with 50 points (23+27) in 77 games.
I didn't see anything saying where he'd report to, but I'm guessing the Pens will have to keep him on the NHL roster. This will either put Malkin onto the IR (he would be eligible to come off anytime), or mean that Ouellet or Stewart will be demoted to Wilkes-Barre. Sabourin being sent down is another possibility.