LMAO, you guys..all the new bills have water marks like that, there's also plastic trip imbedded into the bill with the face amount printed on it. Also some where in the main portrait, there is micro printing that says "The United States of America." This is so small that if you put the bill in a copy machine and copied it, it would look like a black line. Abe has it to the left and right of his name. Hamilton is just above his name. Jackson is kinda like Abe's on either side of his name. Grant is tricky. His is on his collar. I don't hav any Benjamins with me so I can't tell you exactly where his is.
Also on the 10's 20's 50's and 100's the bottom right number, if you twist the bill, it chages colors from green to black. There are still the colored fibers imbedded into the bill, and if you run your finger on their collars you will feel they are textured, not just flat. These are the ones off the top of my head. If I remember anymore I'll post them for you.
Can you tell I used to work for a bank? [;)]