As I was writing this, I remembered a thread from our message forum in 2005 where a customer asked if they could upload more than 2TB of photos under our "unlimited" plan. Remember, this was in 2005.
Here are my replies(tl;dr: Yes!):
1) http://www.dgrin.com/showpost.php?s=14872c114ae3fe4ff300ac6f...
2) http://www.dgrin.com/showpost.php?p=218132&postcount=16
[edited to add 2nd reply since it seemed relevant]