No. No I cannot... :-P
Oh alright then...
Live Effects are plugins or filters which can be applied to objects or bitmaps and can be edited or remove at any time.
For example: I create the text "Pirate Forum" and then add a drop shadow. But I'm not happy with the drop shadow so I go back and change the settings. The shadow updates and I haven't had to undo or recreate anything.
Similiarly, I add a word "Eurobricks Pirate Forum" and the shadow is automatically added to "Eurobricks". I then make the text bold and the shadow automatically adjusts to the new thickness of the text.
I understand Photoshop has limited ability to do this. I.e. there are a range of effects you can add to a layer, but with Live Effects you can add most effects/plugins to any object and change them whenever you please without having to "undo" anything.