It is my understanding that lifts are NOT allowed in true ballroom dancing competitions. The rules state that a dancer must have at least one foot (or at least a toe) in contact with the floor at all times. However, lifts are permitted in "show" dances such as showcases. That's one reason I don't particularly like "Dancing With The Stars" because non-dancers think that the routines with lifts are what makes up ballroom dancing.
All that being said, I have been taking lessons for over 7 years and I cannot convince myself to do a lift with my pro partner, even though she weighs very little. My wife, on the other hand, has done many showcases at competitions that contain several lifts and she loves them. Lifts look great and always entertain the audience. One of my wife's favorite showcases involves her with 6 male teachers with many, many lifts involved.