It seems to be a new trend among facebook developers to place ads outside of the canvas page with CSS absolute positioning. I wonder how long activity like this will go on before facebook blocks it with their parser...
Most of the ads are placed outside of the Facebook canvas page, yes? That space is off limits for developers. So I guess that makes this a TOS-violating app and is also a TOS violation for any developers who place the ads on their applications. Without changes, I don't think Facebook will let this stick around very long.