I don't like that the Shift key doesn't turn itself off after you've typed in a letter. I think this is standard behavior (as standard as it can be, I suppose).
If you want to implement Caps Lock, add a dedicated key or switch modes based on how many times the Shift key is pressed in a row (like T9 on a cell phone).
Cap lock key
This is one of the issues being argued over and over during the design phase. Your input just put some extra weight on one side of the balance. :)