I'm trying to figure out what the name of this type of element is. If the user couldn't do anything else on the screen without dealing with the element, it would be a "modal". Some might call this a pop-up.
This element points at a specific UI element and provides information about this. It's like an über tooltip. Similar to balloon help in the classic Mac OS days. I imagine this type of element is common enough there must be a specific name for it. What is that name?