Dream Cloud is a term I made up to describe vague looking central type moves. Usually White plays them, especially in handicap games. Many times when Black tries to cut them, White finds some way to play lightly and gets a good result. The Black player can feel like he's trying to cut clouds.
Here is a an even game I played where White did this, I was confused about how to handle the situation.
http://eidogo.com/#url:http://files.gokgs.com/games/2009/4/28/gojin-yoyoma.sgf