http://infinite-labs.net/afloat/
Install this app on your Mac, and while you’re running the Corona Simulator with Terminal open, you can make the Terminal app stay on top of the Corona Simulator. This makes it easy to keep tabs on console output without having to switch back and forth between two windows, especially when you’re lacking screen real estate.
I develop on an 11" MacBook Air and the Simulator takes most of the screen when running my app, but with Afloat, I can keep Terminal always on top of it, even when I’m interacting with the Simulator. You can also make the Terminal window transparent, among other things.
Though not mentioned, it does work with OS X Mountain Lion 10.8 and nearly any app you use.