DLC in your game

How would I go about making new level available as DLC in my game? Is it even possible? Wouldn’t those level need to be in the list of levels to build when you initially build your game?

also, what do you guys think about this

http://www.openfeint.com/developers/ios/ofx

Has anybody ever used it for DLC in there games before?

Its possible but you must own Unity Pro commonly so you can use asset bundles

and I doubt many have used it as its extremely new (the mail on it went out like last week to OF developers)