It's History Baby!
If you’d like to see what you’ve done in Lightroom there actually is a History panel. Say you’re in the Develop module and you’d like to jump back to a specific point in the editing history of your Photo. Well right next to the world Presets you’ll see History. Just click on it and Lightroom will display the history states that your image has gone through. Just like Photoshop (what can I say, I’m a Photoshop junkie too). This really helps though when you’re not sure what point you want to step back to and you don’t feel like pressing Control/Command – Z a bunch of times. Just look for the specific step in the History and click on it to jump to that point.