Man, does Mason sound like Jake from Avatar. Could just be the NY accent, but all too often I feel like I'm hearing Jake when Mason is talking. I have only watched Avatar about 100 times, so his voice it engrained into my brain.
I know this has been a popular topic for conversation, but I didn't see it mention here so far.
EDIT:
Yes... it is Sam. He is in the credits.
As is Ed Harris and Gary Oldman who voices I also recognized during the single player campaign.
Speaking of credits... I am always amazed at how many people work on these projects!