It actually sticks up from the top of the camera, like an external flash would. The times I've used it, for landscapes/sunsets, I will set up the tripod, then put the camera on, pop on the bubble, make necessary adjustments, then pop it off and put it back in my pocket or bag. I don't have an external flash, so I could just leave it on for the duration of the shoot...did that once, and forgot to take it off. The bag didn't close as well with it on, though!
The one below is just a quick Google-search grab....the one I have isn't quite as wide, its only about as wide as the flash mount itself, so the built-in flash had no trouble popping up with the leveler on.